Actually, that strategy is likely to get you killed if you just do that. A better strategy would be alternate between the two, such that when you kill one, the other is mostly dead. This will avoid their evil little Solo Phase, where the two swords combine. Alternatively, you could attack one til its near dead, then shift to the other...just don't let one be alive with too much health.
(Did it that way in case you don't want to be spoiled on how to approach the fight, dunno if you want hints or not)
The knock sword out of hand part, mind is actually a sound method, though might I recommend you try Helm Splitters (diving slash move with Rebellion)? Seems to be better at repelling the sword, and I think it doesn't force you into those deflection locks like basic attacks do.