Possible barter practice bug

<100%hp 100%m 100%mv 7843tnl> practice backhand bone You can't practice backhand bone. <100%hp 100%m 100%mv 7843tnl> i You are carrying: a bone from the skeleton of the Snow Worm ( 4) a bowl of Nankorf a mithril saber a metal canteen insulated in a wolf's pelt a notched axe with a wicked blade a practice dagger the belt of life a cowhide knapsack <100%hp 100%m 100%mv 7843tnl> practice backhand saber The guildmaster nods at you with approval. You hand a mithril saber to I couldn't use my snow worm mace to practice backhand.