i was playing against a guy and had bloodthirsty blade on my champ and when i purged impervious got dispelled is that normal?
I would say, that looking at the description, it shouldn't be WAI, it says "equipped champion is... impervious" I understand that as if the impervious condition were linked to the existence of the equipment and that it would apply automatically again after being dispelled. However, from a balance perspective, it's better if it's dispellable, IMO.
It makes sense, though realize bloodthirsty blade now has three counters -- it comes with its own counter (not destroying anything) and can get removed with equipment removal, and dispel. So it's basically just spot multiattack for the equip cost.