[HoneyBadger]

Yeah, that's true-a dagger is a noble's weapon, you use them to finish off your heavily armored opponent after you've knocked him to the ground/senseless, by finding a weakspot in his armor.

I could probably find a dozen different names for fighting-knives, but yes, assassins are going to be relatively poor, and daggers were quite expensive-no reason to use them when you can use something cheap you can discard if you have to.