Well, typically the blunt end of the knife goes in your hand and the pointy end of the knife goes in their...wherever you want to put it really, it's more an art than a science.
True Romans use Gladii
Literally, "How are we obliged to fight?"? Although, I'm not sure that works either.
Is pugnare the infinitive here?
Present active infinitive, yes.
Why not Quomodo pugnamus debemus?