Implement's <Someone>'s suggestion that the currently wielded
weapon be included among the list of inventory candidates for the
wield command. It affects the list of letters shown in the prompt
and the subset inventory displayed if you respond with '?'; it doesn't
change how wielding works or what item you can pick to wield.
Do the same thing for quivering: include any currently quivered
item among the choices. Also include the secondary weapon as a choice
if you're not actively two-weaponing.