Honestly, I think it would be best to wait another arc or two so we get to see his magic some more.
I think against Talisker, his magic was boosted because of the potion, that's why he was overflowing with so much magic, compared to the first time where he only has enough magic to either spread a thin layer over his whole body, or focus it on his hands.
Also this "Energy Blade: Creates a massive energy blade causing multiple slashes to his opponent with one slash."
It didn't happen in one slash, it was multiple slashes (9 slashes going by Percival saying "bap" that many times).
There is though. After he drank the potion, he became highly energetic, exclaiming that he can "feel the power surging through him from head to toe".
Later, he goes on to activate his magic in the fight, with it being specifically noted that he producing way more than the first time, along with it visually overflowing like crazy.
We can wait to see what happens when he's next in a fight, but I highly doubt he will be producing the same amounts of magic as he did against Talisker.