Are you trying to modify the gear equipped or the gear that drops on death? Treasure tables control what pseudo-random loot drops. If you want to modify the gear that an NPC has equipped, I believe you want to look into modifying the 'Equipment' table row associated with that NPC. Keep in mind it will change the equipment for all NPCs that use that row, so if you want it to be unique, you probably want to create a new one and assign that to the NPC.
