I like battlemage type too. It was instantly alluring for me when I played The Witcher 2 for the first time. The guy wasn't only good with his swords, but also could enchant stuff, use alchemy. But since the showrunner said they're adapting the books, not games, we shouldn't exclude the possibility of them toning down his abilities. Either way, I'm pretty sure he will use stuff like "force push" or "quen". Putting people to sleep a la Kylo Ren. But I seriously doubt about fire or lightning bolts.