Masks can alter how powerful a being is. Vadderung as Odin may be more powerful than Kringle.
In the pantheons, all the gods draw from the same source. How close they are to that source determines how powerful they are. Zeus is in control of that source, so he is the most powerful, Poseidon and Hades close behind. Hecate is farther from Zeus, so she has less access to that power source.
In her MW mask, she is far closer to the Winter power source, so she is way more powerful, more like Zeus. If Hecate went against Hades on his turf she would lose. If Hades went against MW on her turf, he would lose.