As a detailed description

Give the artifact a title, either something descriptive ("a stone cup") or a proper name ("the Red Pennant"). Assign it tags, load (if any), and other game elements (see Tags). Then write a few sentences about it, what it looks like, what it does (if anything), what that involves, and why it's useful, interesting, and/or valuable.

Consider writing "something interesting" and "something useful" about the artifact, if you suspect that the PCs will Know Things about it.

For examples, see a spindle of fine thread, or an oversized ring.

I create another artifact that the PCs could find in the old tomb, something interred with the Green Lord itself.

I run through the first three steps and end up with an origin of Aratis and a theme of "laws/rules/traditions." It's redwood, with an extraordinary property of "fills those who look upon it with __." It's "a item," with a form of "Fire: incense, oil, candle, lamp, lantern, sconce, brazier, hearth, etc."

Interesting! Apparently, this Green Lord revered Aratis, the god of civilization and order. Redwood is "a natural tether for spirits of the wild," and fire is often a symbol of chaos. But taming fire is a very "civilized" thing to do, and the Green Lords did harness spirits to do their bidding. I think this is a brazier, binding a fire spirit sanctified to Aratis.