Answers to questions like What should the rarity rating be for this homebrew Healing Brick? are usually based on comparison of effects of an item. On the other hand, there are questions like
- The power level of the Sword of Sharpness doesn't justify its very rare rating - am I missing something?,
- Handy Haversack vs. Bag of Holding and
- Why is this uncommon magic item better than this rare magic item?
that make me doubt if rarity is really tied to power*.
Is there any rule or guideline that says more powerful items should have a higher rarity (or that rare items are more powerful than less rare items)? For example, if I have a legendary item can I say for sure that it is more powerful than items in the lower rarity tiers? Or can rarity also be indicative of other factors besides power?
I'm looking for general rule or guideline, or lack of it.
* If definition of item's power is needed, use the same definition that is applicable to the word on DMG p135.