If he mastered magic he would be doing as much damage as a level 500 person would (he’s likely around that area considering all the things he’s unlocked). I believe Calvus truly didn’t even try mastering anything he has. Instead of finding powers he likes and sticking to them, he would probably always replace them. A mod said there’s likely a potion that lets players remove their lost/ancient magic to return to base in case they want to try out a different lost/ancient, and I head-canon Calvus used that a lot. I’ll bet Aether wasn’t even his main power, he picked a different lost magic to use every week or something stupid. Maybe he learned Iron Leg while on his trip away from the kingdom and only knows how to use Smash with it.
Also, the protagonist is probably descended from a god, and their “special blood” is ichor, hence why Calvus’ text turns golden when he says “your blood”