Crothian said:
There is no right answer. I've handed out artifacts at all level of play to see what happens. I've found it's more about the PCs and their characters then level. And the artifact does make a difference, some are really supre powerful, others are not that great.
This is right on the money. A lot depends on the PCs, but even more on the artifact itself. If you're talking about an artifact like the
Sword of Kas or somesuch, then the PCs shouldn't see it until the artifact's power is relatively in line with their own (20th level or so.)
But some artifacts have powers that are less directly helpful to the PCs in question. One of the Storyhours features an artifact called the
Crosser's Maze, which is powerful enough to reweave planar boundaries, but provides no real benefit for the wielder in combat.
In a campaign I played in last year, my PC had a minor artifact called the
Pearl of Pure Light. It acted as a movable consecretion, and allowed the wielder to turn undead as a cleric of two levels lower. As our party didn't have a cleric and were fighting a lot of undead, it basically allowed the rogue to become a stand-in cleric in regards to turning undead. Not game-breaking at all, and something that could have been done at any level.
So I'd say the most important thing is to consider what type of minor artifact you're dealing with, and whether it's powers will unbalance the game. If it's a combat item (
Sword of Kas), be careful. If it's a plot item (
Crosser's Maze,) then less concern with level is necessary.