Attaque Composee normally deals two hits.
Misrus Rapier effect adds two hits to Attaque Composee.
Offensive Rapide doubles the hits by fencer skills, albeit lowering their normal damage to 70% when maxed.
The expected result would be for Attaque Composee to deal 8 hits, at 70% of the normal damage, when Offensive Rapide is toggled on…
But i just tested it, and it does 6 hits at 70% damage. So it takes the drawback of Offensive Rapide, but doesn’t get the additional hits that would make for it. Doesn’t make much sense for it to work that way, so it’s clearly a bug, especially given the other poor stats given by the weapon in question.
Yeah, it feels under the expectative:
Just as an extra here is Skiaclipse Rapier 
The description says it adds two hits. Since this is tos, it’s expected to be some kind of additional hit that doesn’t care about the fencer’s attribute.
I would agree with that if the added hits completely ignored the attribute. But they don’t.
They’re still affected by the attribute’s damage reduction.