Credit to bunjimon for mentioning the night vision. The idea would be an enchanted leather, or iron, helmet that provides night vision to the wearer. Would be unique, and very useful for mining and such. Could be balanced with low armor stat (if leather), but still be powerful as it alleviates the need for torches. If that's still too op, then maybe it could give the effect for 16 minutes or so (same duration as the potion of super fire resistance) I've never been to one of the big EMC parties where new promos are handed out, but I have an Aikar's Scuba Hat from the last one. In my opinion, it should have had Respiration V, or similar, to make it a bit more powerful than a normal turtle shell. For whenever the next big EMC party is, maybe 10th anniversary, I think this is a good idea for a rare drop
+0 to your suggestion; I can see the benefits of it, but I don't think I would use it personally. About your example specifically, though, I just wanted to mention that the Aikar Scuba Hat is one of, if not the most overpowered custom item... it's unbreakable and soulbound, and unbreakable things are supposed to have lesser enchants than vanilla diamond stuff would, because it's unbreakable..
+1 I think this would be great as I always run out of lighting. I do think that an infinite night vision, might be a little too op, but I think it's great. Another good use for this would be searching within oceans, you are able to see clearly with night vision and it makes going under great.