Anyone remember the elevator pass from SK's past well this is basically the same thing. For a set time when weapons reach their required heat to level up they do so without the use of fire crystals
*hides and leaves a sign behind himself saying, "Judge!" *
Maybe fire crystal, but yeah. I disagree on automatic level ups, but having rarities move backwards one stratum would be nice. And since loot is instanced anyways, only you could benefit.
Granted if Three Rings fixes the lack of radiants, this item would be sort of useless.