People seem to generally consider artifacts as game breakers: they are just way too powerful for the group and make the game too easy in any of a variety of ways (bypassing challenge, divining them, too efficient in combat, w/e).
I don't see it that way. Artifacts are not stat boosters or free spells for PCs. They are opportunities for adventures, triggers to all sorts of complications in the game that will make it interesting in any of a number of ways. Thing is, they don't have to be obviously awesome and used right away by the PCs. The artifact may for instance be powerful enough to obfuscate its abilities, and/or appear as a completely mundane item. They might be acquired by the PCs before they find out anything about them that would allow them to actually use/channel their powers.
I think artifacts may be acquired at any level by the PCs, but their powers might not be obvious, or might need to grow over time as the PCs study it, discover its history and significance in the world, or their minds meld with it, or it gains sentience, or whatever the case may be.
Example: Pei Lin, my wife's character, actually started the game with an artifact, the Jade Lantern, a ball of dark emerald she retrieved from Liu Xin Tsao's tomb on
Level 2 of St. Makhab's Tower. This actually was the item her expedition was searching for before it was completely wiped out and she lost her memories (at which point the actual game starts). Now, either she explores the world without ever worrying about what happened before her character lost her memories, goes on other adventures in the sandbox etc, or she starts wondering about what this item exactly is, investigates its significance, who she was prior to her "accident", etc, at which point she could come in contact with some forces associated with the Black Abbey who want the Jade Lantern for themselves.
My point is, artifacts are major building blocks of a campaign, like major NPCs themselves really. As such, they can be introduced to the PCs at any point of their career, if done properly.
While I've seen some sweet unique magical weapons at level 5 (S2) The lowest level I've seen one introduced is level 6-10 (Daoud's Lanthorn in S4). I'm sure one of you will write if you know of a published instance where an artifact was introduced at a lower character level.
