With or without a weapon, the technique should work in the same way.
You know, I fundamentally agree with this statement insofar as it goes.
The consequences of a mistake are radically different. I've blown an entry and wound up taking a punch to my body and then followed that up by tossing my attacker (okay, I'll admit it, sometimes I threw them a bit hard
when their punch actually landed
). If the punch had been a knife, I might have been dead and I certainly would have been seriously injured.
Although, it occurs to me that such incidents were in training. The few of times when I was facing a serious challenge no punches (or kicks) ever landed. Still, that might have been dumb luck.
So, yeah, the techniques work the same, but you just don't have the margin for error against weapons. Hey, maybe that's a good reason to train against weapons?