1. Basic vice admirals have armament and observation. Kobyvhas both including advanced observation.
2. Law's entire fighting stylenafter wards including speed relies on his devil fruit. The only hit law took point blank from a yonko is a her punching him.
His entire mauerability, speed, defense ,offense and AP is devil fruit oriented.
Why are you mentioning koby? I never once brought him up. Also if you mean the whole vanishing voices thing.
Big Mom punches, especially punches coated in armament aren't something to scoff at considering her armament could just stop WCI G4 Boundman luffy cold.
And here is Law, with his room elsewhere, cutting Misery, a combined homie, in half.
I'm not saying Law isn't weaker. Hell, I'm not sure I'd even say he's Jinbei tier, but he's got a lot more going for him than Franky even without his DF.