Malgus is a tank, able to recieve hundreds of rocks and then be completely fine. Even if the Jedi was fatigued, Malgus was able to take down Kao Cen Darach (Which I'm assuming you also underestimate), a Battlemaster.
Malgus was able to handle a PEM (Or whatever that grenade was) right on his face. Plus, the Malgus I'm using is Prime Malgus, not the one on the first TOR trailer or something.
He was able to defeat Ven Zallow, one of the best Jedi of the time, he may not have done this with ease, but it still wasn't something super hard