HyperConomy allows a player to purchase an enchantment for an item that it can't legally be applied to. For example, purchasing knockback for an axe.

IMO, enchantments should be restricted to items that they can legally be applied to as shown on the following page:

http://minecraft.gamepedia.com/Enchanting#Summary_of_enchantments

This is an old issue, does not have recent activity, and I'm not even sure the original issue is valid anymore. Closing this issue to save work for the maintainers.