Something I encountered while playing slash'em a while back, but
relevant to nethack: "Its orcish spears shatter from the force of your
blow!". I was using a two-handed weapon (at skilled or expert level) to
fight an invisible monster which was wielding a stack of multiple spears
(slash'em gives them out in groups of 3 for monsters' starting inventory).
After killing it, I found 2 orcish spears along with an invisible corpse
of somebody-or-other the Kobold King. The message suggested that the
whole spear stack had been destroyed (and the weapon shattering code in
hmon_hitmon() clearly expects that to be the case), but only one of them
had actually gotten used up.
I can't recall whether "shatter" was actually given as singular or
plural at the time; nethack handles that aspect correctly. Only object
destruction needed tweaking.