As long as new artifacts are being added (thus reducing the odds that a vault or a precrowning will give one of the old favorites like the famed shining silver bracers, the sapphire amulet, or the fine leather armor), how about clearing away some of the artifacts that are really useless?

Silver key: A key that can open any door sounds awesome, but in ADOM, that only duplicates the effect of having six regular keys. There's no real way to make this artifact anything but a disappointment to the player who gets it.

Thunderstroke/True Aim: Widely considered useless. Various other ideas have been suggested for good artifacts for archers -- these just need to go. It pretty much never makes sense to use ammo that won't stack with anything, since reloading takes time. No one uses these. How would they ever achieve legendary status with no archer in their right mind using them?

Soaker/Scorched Spear/Long Sting/Cat's Claw/Black Thumb: There are a bunch of artifact weapons that just don't make sense to use. There's no real reason to use these items; I don't see any way (or reason) to save them.

Nature's Friend: Lust for Glory has wussy numbers but it actually makes sense to use because it has some really valuable resistances -- dual wielding it with a higher DV shield actually makes serious sense for spellcasters. Nature's Friend is similar, except that its resistances aren't useful. Alternatively, it could be made significantly more powerful, since there are few artifact shields -- but it's depressingly useless as is.

The Black Tome and Shezestriakis: I actually really like these for story reasons. I think it'd be worth making them more powerful so that they it no longer is an absolutely idiotic choice from a gameplay perspective to actually use them, but whether they change or not, I'd be sad to see them go.