Personal Experience is for Daggers, Evis > Aeolian Edge by far. @85 I was able to get 450~500 outside abyssea with AE in my nuking set. If I used Martials Dagger then I can make it go higher, but your TP damage will suck. Evis I can hit 700+ easily, higher if its a T or below monster. DB I haven't tested in a long time, I'll probably do some of that later. CDC is by far my best WS though, every RDM should making getting access to that a priority. And honestly short of SE giving us access to the EX weapons skills (Vorpal) our sword WS really takes a hit. Evis would beat out DB if we had access to better daggers.

Also to answer your question, yes magic accuracy helps magic WS. It's a generic stat, it effects all spells cast, enspells, and even any additional effects from ammo / weapons you have. This is why I full time the Mag Acc +8 chakram.