Daredevil is more technically skilled. There is no doubt about that. But Slade has a big strength advantage on him, smarter, is the better tactitian, and has a healing factor. I'd tend to say he has better reflexes as well but I won't argue who is faster. Agility is one of Daredevil's calling cards but Deathstroke is no slouch in that area either. He's temporarily evaded Superman.
The guy knocked Batman out before the upgrades.