Not sure why you distinguish "Items" from "Weapons" from "Armor" as table types . . .

My guess is that (being this is for an RPG), 'weapons' and 'armor' have to store certain modifiers (like "+3 magic defense, -2 speed") which might not make sense for the other categories. Unifying the tables while handling modifiers elegantly probably isn't easy.

Update: Actually, now that I've thought about it a bit longer, the actual attributes of the various item types are probably going to be static, so there's little sense in putting them in the database. Instead, they should probably be in a configuration file, and the data in the file related to the items in a store. This should be easy to do with Class::DBI, since it doesn't say that classes in a relationship with the current class must use a database.