Virtue Artifacts are artifacts that drop in the Anti-Virtue Dungeons, which are also known as the Dungeons of Sin, or the "legacy" dungeons. The Virtue Artifacts began appearing as part of the 10th Anniversary celebration. Most were connected in some way with a figure from Ultima Online / Ultima Prime (such as Jaana and Katrina), or with Virtues in general.
"For your valor in defeating the fallen creature, you have been rewarded with a special artifact."
If your pack is full the artifact will be placed in your Bank Box instead.
A hidden counter is incremented with each kill you make. The higher the counter is, the more likely you will receive an item with your next kill. Creatures with higher levels of fame increase the counter faster, though killing while hidden (as is possible with pets) will result in fewer "points" being earned. The counter resets to zero when an artifact is achieved.
Although some are technically level 11 artifacts (the highest known), they are not considered terribly valuable due to the low difficulty involved in acquiring them. It has been mentioned that some items will be removed from the list in future (to be replaced with others), but there has been no indication as to when this will happen.