alsih2o said:
I've got a distinction between "relic" and "artifact". A relic tends to have religious or sociological significance and is more likely to have been used in the past and have tales and legends told about it. An artifact on the other hand is simply a leftover thing from a bygone era. Its appearance in a game world is more of an unexptected event, unheralded by legend or prophecy, but ends up having the same kind of impact on a world as a relic simply due to its great powers.
So the Mace of Cuthbert would be a relic - a legendary weapon known by all to have been wielded by the Saint-turned-deity, with tales not just of use by Cuthbert by mortals who may have used it - or who are destined to use it in the future.
The Hand and Eye of Vecna are relics, again because they have well-known legends associated with them, their powers are almost certainly detailed in any number of accounts (though they may well all be dead wrong) and there are likely tales regarding what happened in the past when people encountered them.
The Machine of Lum the Mad on the other hand is an artifact. There may be information about it recorded in forgotten tomes but generally isn't known about by anyone until it actually surfaces in someones possession who makes use of it. It may have been used long ago at length but there's no prophecy about it being used again, no tales of it having been used since ancient days, and little or no knowledge of what it is or does - even inaccurate knowledge.
Just my own thoughts on the matter...
Personally, I've almost never used artifacts or relics in my campaigns anyway - I certainly can't recall any that I've let actually become a significant part of the game. I've played in campaigns where they HAVE come into play and generally seen those campaigns go into tailspins when they do. Either they just bump power levels up to unreasonable levels, or if power levels already are at unusually high levels they fail to serve the purpose of being adventure or campaign foci - they become merely another powerful tool in PC/NPC arsenals and the game loses some of its touch with reality. Just my experience with it - yours may vary. As such I've never had need to actually design my own.