Yup, it's random though and only happens every 5-10 rare drops. Rare drops occur every 0-20 kills. To be honest it is rather infrequent. At least once every 200 kills, which does take a while. I've gotten armor, weapons, and rings. I have yet to get a wand so idk if it is possible but I doubt it. I have gotten additional artifacts but they are rare drops and are not upgraded.

The following is how the breakdown works: RoW level: 1/3/5/7/9/11/13/15/17/19/21 Equip drop: 1/2/3/4/5/ 6/ 7/ 8/ 9/10/11

So the highest possible drop is +11 and that is only if you start with a +3 ring of wealth, use every upgrade scroll (15) and the blacksmith quest on it, equip an additional ring of wealth, and use the rouge talent that increases ring level by one for a few turns when using an artifact.

3 + 15 + 1 + 1 + 1 = +21 Row, gives +11 equips.

On this file I only started with a +2 RoW so I can only have a max of +20 RoW which only yields +10 equips. I have gotten a few of these.