diff --git a/include/extern.h b/include/extern.h
index 28c8c8c8b..6887b02d0 100644
--- a/include/extern.h
+++ b/include/extern.h
@@ -1773,6 +1773,7 @@ extern boolean defended(struct monst *, int) NONNULLARG1;
 extern boolean resists_drli(struct monst *) NONNULLARG1;
 extern boolean resists_magm(struct monst *) NONNULLARG1;
 extern boolean resists_blnd(struct monst *) NONNULLARG1;
+extern boolean resists_blnd_by_arti(struct monst *) NONNULLARG1;
 extern boolean can_blnd(struct monst *, struct monst *,
                         uchar, struct obj *) NONNULLARG2;
 extern boolean ranged_attk(struct permonst *) NONNULLARG1;
@@ -3829,7 +3830,7 @@ extern int dozap(void);
 extern int zapyourself(struct obj *, boolean) NONNULLARG1;
 extern void ubreatheu(struct attack *) NONNULLARG1;
 extern int lightdamage(struct obj *, boolean, int) NONNULLARG1;
-extern boolean flashburn(long);
+extern boolean flashburn(long, boolean);
 extern boolean cancel_monst(struct monst *, struct obj *, boolean, boolean,
                             boolean) NONNULLARG12;
 extern void zapsetup(void);
diff --git a/src/artifact.c b/src/artifact.c
index 40b46a44d..6764d8762 100644
--- a/src/artifact.c
+++ b/src/artifact.c
@@ -1942,7 +1942,8 @@ arti_invoke(struct obj *obj)
                     if (vulnerable) /* could be fatal if Unchanging */
                         (void) lightdamage(obj, TRUE, 2 * damg);
 
-                    if (!flashburn((long) (damg + rnd(damg))) && !vulnerable)
+                    if (!flashburn((long) (damg + rnd(damg)), FALSE)
+                        && !vulnerable)
                         pline("%s", nothing_seems_to_happen);
                 }
             } else {
diff --git a/src/mcastu.c b/src/mcastu.c
index f9b315c65..d686ced9d 100644
--- a/src/mcastu.c
+++ b/src/mcastu.c
@@ -688,7 +688,7 @@ cast_cleric_spell(struct monst *mtmp, int dmg, int spellnum)
            do this before maybe blinding the hero via flashburn() */
         mon_spell_hits_spot(mtmp, AD_ELEC, u.ux, u.uy);
         /* blind hero; no effect if already blind */
-        (void) flashburn((long) rnd(100));
+        (void) flashburn((long) rnd(100), TRUE);
         break;
     }
     case CLC_CURSE_ITEMS:
diff --git a/src/mondata.c b/src/mondata.c
index 0b8136dcd..07a3259a3 100644
--- a/src/mondata.c
+++ b/src/mondata.c
@@ -170,14 +170,13 @@ resists_magm(struct monst *mon)
     return FALSE;
 }
 
-/* True iff monster is resistant to light-induced blindness */
+/* True iff monster is resistant to light-induced blindness due to some
+   mundane reason (already blinded) */
 boolean
 resists_blnd(struct monst *mon)
 {
     struct permonst *ptr = mon->data;
     boolean is_you = (mon == &gy.youmonst);
-    long slotmask;
-    struct obj *o;
 
     if (is_you ? (Blind || Unaware)
                : (mon->mblinded || !mon->mcansee || !haseyes(ptr)
@@ -189,21 +188,32 @@ resists_blnd(struct monst *mon)
     if (dmgtype_fromattack(ptr, AD_BLND, AT_EXPL)
         || dmgtype_fromattack(ptr, AD_BLND, AT_GAZE))
         return TRUE;
+    return resists_blnd_by_arti(mon);
+}
+
+/* True iff monster is resistant to light-induced blindness due to worn
+   or wielded magical equipment (used to decide whether to show sparkle
+   animation when resisting) */
+boolean
+resists_blnd_by_arti(struct monst *mon)
+{
+    struct obj *o;
+    boolean is_you = (mon == &gy.youmonst);
+
     o = is_you ? uwep : MON_WEP(mon);
     if (o && o->oartifact && defends(AD_BLND, o))
         return TRUE;
     o = is_you ? gi.invent : mon->minvent;
-    slotmask = W_ARMOR | W_ACCESSORY;
-    if (!is_you /* assumes monsters don't wield non-weapons */
-        || (uwep && (uwep->oclass == WEAPON_CLASS || is_weptool(uwep))))
-        slotmask |= W_WEP;
-    if (is_you && u.twoweap)
-        slotmask |= W_SWAPWEP;
     for (; o; o = o->nobj)
-        if (((o->owornmask & slotmask) != 0L
-             && objects[o->otyp].oc_oprop == BLINDED)
-            || (o->oartifact && defends_when_carried(AD_BLND, o)))
+        if (defends_when_carried(AD_BLND, o))
             return TRUE;
+#if 0   /* omit this; the Eyes of the Overworld have no carry property and
+         * their worn property is magic resistance rather than blindness
+         * resistance; wearing them blocks blindness without actually
+         * preventing it, so don't classify them as providing resistance */
+    if (is_you && is_art(uamul, ART_EYES_OF_THE_OVERWORLD))
+        return TRUE;
+#endif /* 0 */
     return FALSE;
 }
 
diff --git a/src/uhitm.c b/src/uhitm.c
index adf0cd0eb..7f33c8777 100644
--- a/src/uhitm.c
+++ b/src/uhitm.c
@@ -6097,17 +6097,17 @@ flash_hits_mon(
     struct obj *otmp) /* source of flash */
 {
     struct rm *lev;
+    coordxy mx = mtmp->mx, my = mtmp->my;
     int tmp, amt, useeit, res = 0;
 
     if (gn.notonhead)
         return 0;
-    lev = &levl[mtmp->mx][mtmp->my];
+    lev = &levl[mx][my];
     useeit = canseemon(mtmp);
 
     if (M_AP_TYPE(mtmp) != M_AP_NOTHING) {
         char whatbuf[BUFSZ];
-        coordxy x = mtmp->mx, y = mtmp->my;
-        int oldglyph = glyph_at(x, y);
+        int oldglyph = glyph_at(mx, my);
 
         /* 'altmon' probably doesn't matter here because 'whatbuf' will
            only be shown if the glyph changes and wakeup() doesn't call
@@ -6118,13 +6118,14 @@ flash_hits_mon(
                               * finish_meating() to end quickmimic */
 
         /* if glyph has changed then hero saw something happen */
-        if (glyph_at(x, y) != oldglyph)
+        if (glyph_at(mx, my) != oldglyph) {
             pline("That %s is really %s%c", whatbuf,
                   /* y_monnam()+a_monnam() */
                   x_monnam(mtmp, mtmp->mtame ? ARTICLE_YOUR : ARTICLE_A,
                            (char *) 0, 0, FALSE),
                   mtmp->mtame ? '.' : '!');
-        res = 1; /* mtmp is affected whether hero sees it or not */
+            res = 1;
+        }
     }
 
     if (mtmp->msleeping && haseyes(mtmp->data)) {
@@ -6135,15 +6136,15 @@ flash_hits_mon(
         }
     } else if (mtmp->data->mlet != S_LIGHT) {
         if (!resists_blnd(mtmp)) {
-            tmp = dist2(otmp->ox, otmp->oy, mtmp->mx, mtmp->my);
+            tmp = dist2(otmp->ox, otmp->oy, mx, my);
             if (useeit) {
                 pline("%s is blinded by the flash!", Monnam(mtmp));
                 res = 1;
             }
             if (mtmp->data == &mons[PM_GREMLIN]) {
                 /* Rule #1: Keep them out of the light. */
-                amt = otmp->otyp == WAN_LIGHT ? d(1 + otmp->spe, 4)
-                                              : rn2(min(mtmp->mhp, 4));
+                amt = (otmp->otyp == WAN_LIGHT) ? d(1 + otmp->spe, 4)
+                                                : rnd(min(mtmp->mhp, 4));
                 light_hits_gremlin(mtmp, amt);
             }
             if (!DEADMONSTER(mtmp)) {
@@ -6154,12 +6155,16 @@ flash_hits_mon(
                 mtmp->mcansee = 0;
                 mtmp->mblinded = (tmp < 3) ? 0 : rnd(1 + 50 / tmp);
             }
-        } else if (flags.verbose && useeit) {
-            if (lev->lit)
-                pline("The flash of light shines on %s.", mon_nam(mtmp));
-            else
-                pline("%s is illuminated.", Monnam(mtmp));
-            res = 2; /* 'message has been given' temporary value */
+        } else if (useeit) {
+            if (resists_blnd_by_arti(mtmp))
+                shieldeff(mx, my);
+            if (flags.verbose) {
+                if (lev->lit)
+                    pline("The flash of light shines on %s.", mon_nam(mtmp));
+                else
+                    pline("%s is illuminated.", Monnam(mtmp));
+                res = 2; /* 'message has been given' temporary value */
+            }
         }
     }
     if (res) {
diff --git a/src/zap.c b/src/zap.c
index 7e341c630..759f32e6b 100644
--- a/src/zap.c
+++ b/src/zap.c
@@ -2657,7 +2657,7 @@ zapyourself(struct obj *obj, boolean ordinary)
             ugolemeffects(AD_ELEC, orig_dmg);
         }
         (void) destroy_items(&gy.youmonst, AD_ELEC, orig_dmg);
-        (void) flashburn((long) rnd(100));
+        (void) flashburn((long) rnd(100), TRUE);
         break;
 
     case SPE_FIREBALL:
@@ -2836,7 +2836,7 @@ zapyourself(struct obj *obj, boolean ordinary)
             damage = 5;
         damage = lightdamage(obj, ordinary, damage);
         damage += rnd(25);
-        if (flashburn((long) damage))
+        if (flashburn((long) damage, FALSE))
             learn_it = TRUE;
         damage = 0; /* reset */
         break;
@@ -2971,7 +2971,7 @@ lightdamage(
 
 /* light[ning] causes blindness */
 boolean
-flashburn(long duration)
+flashburn(long duration, boolean via_lightning)
 {
     if (!resists_blnd(&gy.youmonst)) {
         You(are_blinded_by_the_flash);
@@ -2980,6 +2980,16 @@ flashburn(long duration)
             Your1(vision_clears);
         return TRUE;
     }
+    /* if blinding is resisted due to magical equipment (Sunsword), give
+       a sparkle animation (even if also resisted due to being blind)
+       _unless_ this is lightning-induced; we don't want a double sparkle
+       if hero is both lightning resistant and blindness resistant, or
+       worse, have a single sparkle where the player confuses blindness
+       resistance for lightning resistance */
+    if (!via_lightning && resists_blnd_by_arti(&gy.youmonst)) {
+        shieldeff(u.ux, u.uy);
+        return TRUE;
+    }
     return FALSE;
 }
 
@@ -4817,7 +4827,7 @@ dobuzz(
                 Your("%s tingles.", body_part(ARM));
             }
             if (damgtype == ZT_LIGHTNING)
-                (void) flashburn((long) d(nd, 50));
+                (void) flashburn((long) d(nd, 50), TRUE);
             stop_occupation();
             nomul(0);
         }