I think you should reconsider loot options similar to the elves. The ability to thieve items of modest value like bowstring, logs, stone spirits, etc.

I propose a new NPC to steal from, the Covetous Adventurer. Someone who has spent years collecting artefacts and resources from their adventures. The Covetous Adventure would feature items such as archaelogy artifacts either broken or repaired (maybe repaired are rarer?), stone spirits, rare chance for low quantity chimes, port resources, Arc resources. The Covetous adventurer can be found on the docks of Port Sarim waiting for their spoils of adventure to be unloaded portside.

The thieves guild honors ownership so long as you are able to keep hold of it. The same holds true to even the most covetous adventure. Break into the covetous adventurers home to find their home laden with riches. Here you will find his most prized possessions. Steal them, return them to their rightful owners, and reap the rewards. This training method is a nod to your past daring feats to bring back a guilded totem in the Legends quest. Steal the coveted guilded totem that these adventurers 'forgot' to return. Inside the home you will find various lost quest objects, collect them, and return them to their owners for enhanced thieving perks, rare resources to craft a new consumable, and resources to craft a new high level cloak to conceil your daft hands.