Some of our items are restricted by race (why would centaurs want to wear spurs?) and some by alignment (can you see a devil holding a cross?). Also, certain races don't have certain body parts - example, a dwarf does not have antennae, but a martian does. Also, some of our equipment is gained through quests that put a flag on the player that completes that quest so only they can use the item. See help races or help < racename > for more information on races - including unique body parts.