Peter2 is right. Only Mater Archer (or Sniper) can become an expert in Disarm Traps.As far as the item of Disarm for your Archer is concerned, you need "mephistoing". Possibilities:
- Dragons (and Blood Titans) drop level 6 items, you can get an item (up to) +25 from them. The first chance is the EI Dragon, next chance is Wromthrax.
- Magic shops: The shops in Deyja and Bracada Desert sell level 5 items, you can get an item +17 there.
- Item Maker in Erathia. Kergar gives you an item +12, Erudine (there are always a few pieces of Erudine in Erathia) gives you an item +17.