Lol fair enough, I know what you are talking about. I’m unsure if lightsabers are hotter than that. It depends on what your source is

But lightsabers also have a magical element to them, being based off of force sensitive crystals. So would the circumvent their resistance

Depends on if Viltrumites are immune to lightsabers. And if Jedi foresight and reaction speed is enough to block their attacks.