Yeah, I noticed this too when testing CMW. It seems enchants do not adjust to weapon speed, so the ideal CMW/DMB build will probably favor fast dex-focused weapons.
Saw a post on wiki-dot's forums stating that with Rickard's Rapier unique multi-hit R2, the weapon enchant actually gets applied to each hit for some absurd combo damage. Painting Guardian Sword may get similar treatment with its unique R2.
Also, not sure if you saw my post a few pages back, but from my testing, I can confirm that Hornet's Ring at least does increase your static weapon enchant damage by exactly 1.5 when backstabbing/riposting.