I do it in two swords. 3+4 go off the platform 3+3 run like a lil biatch. Grab second sword 4+3 get off platform 3+4. Or go 3+3 go back up 3+3 then next sword go 4+3.
Back when the cap was 32 all I had to do on my hunter was 3 smashes every time and he died consistenly on the last smash. It was simple and effective. If that no longer works, just have someone watch his health and tell you when to stop. He enraged on the C in crota IIRC, anyways just keep him above the engrage point and on the last sword finish him. If you need maximium DPS, use the swing combo, melee, melee, smash.
I must say in my experience being a level 32 hunter with full agility, that If I Hit Crota 14 times by the second sword, 3 smashes then 4 smashes on the first sword and 3 smashes then 4 smashes on the second, HE ENRAGES EVERYTIME ON THE 14TH HIT just saying. SO when I run sword I go for 13 hits with the first 2 swords. doesn't really matter how you get 13 hits just GET 13 hits AND NO MORE, you can get 4-4, 3-2 or 3-4, 3-3. But for me its a guarantee that crota gets enraged on the 14TH HIT