I'd say:
1) Accessible, but difficult to afford, high quality gear.
2) Some wear on your (and other's) gear to generate turn-over in items.
For example, if you come across a bandit, and proceed to Dark Knight him with your +steel short sword+ before bisecting his torso, then the bandit's copper chain mail should be left uselessly tattered afterwards.
If you clobber him with your silver warhammer, it should do some nice damage, but the weapon would become heavily worn/damaged in the process due to the softness of the metal.
Also, you should be able to actually find and buy that +steel short sword+, but it should be expensive in terms of effort.
High quality stuff should have actual value. It should feel like an accomplishment, even if it isn't bragged about when meeting adventurers.
Grabbing an armful of silver weapons from the catacombs and dumping them on the weaponsmith cheapens the value of the acquisition. Buying up the most expensive sword in town with the proceeds of a single Vampire's severed left hand has a similar problem.
Perhaps that means requiring that most merchants don't accept your bloodstained loot, and you have to pawn off equipment at far below market value unless you legitimately own it, or perhaps just used stuff taking a very quick price hit.
Such as: Brand new = 100% price, barely scuffed = 33% price, worn or worse = scrap material value.
That would let you get your money back on pristine items if you mistype, without making it trivial to buy out the whole shop with the loot from a quest or two.