I normally postpone doing the Barrow Downs and the Barrows till I feel strong enough to do them without too much pain. The Barrows shouldn't be done right after clearing your Castle and the surroundings, which might be a common mistake. The Barrows will be too much to handle at this point - the various undead can sometimes swarm you where there is little room for retreating. It's better to deal with stuff in Erathia like the Sewers and the Bandit's Cave. I would also deal with stuff in Tularea incl. the Caves. Also I hope you did the White Cliff Cave after dealing with the Goblins in Harmondale.
If disarm fails all the time in an area like Stone City or really anywhere, just ignore the chests/cabinets while clearing a dungeon for monsters. Then afterwards come back with a Burglar NPC who is free for hire and swoop around opening all chests - just don't grab the gold till you've dismissed him after job well done. I use this trick whenever my disarm skill is too low.