Though it strays into "class balance"
4 new items for the game
For Assassin/Ranger when using a Reverse Sword - Full Dex based, medium HP high SP medium defense medium resist
For hunter/Archer when using Bow/Arch - Full Dex based, medium HP high SP medium resist medium defense
For Pagan/Mage when using Dagger or Staff - Full INT based, medium HP high MP high resist low defense
For Priest/Oracle when using Dagger or Staff - Full WIS based, medium HP high MP, high resist low defense
Reason. The weapons these would be used in conjunction with are the weakest ones in the game, these tiems would equip in the "shield" slot, and would be similarly statted with the usual variance of gear.
Guard/Def and warr/fighter already can equip shields
Javelin/X-Bow very high attack weapons alternatives could have the "quiver item"
Claw (this weapon takes 2 hands and therefore would be excluded)
Benefits, gives more options to class/weapon types generally regarded as "weaker" and allows ALL classes to utilise the "shield" equipment slot that currently only 2 classes can use.