Lol, everyone go back to play SC3 or watch some Sig SC3 matches featuring RSH'A, get familiar with it then go back & check 5:22. I'm 100% positive!! XD
I know & I can recognize all Sig moves like I know my hand & pick-my-nose with my fingers.
at 5:22 see the mid sword swing that hits Patroklos which frames motion & trace-sword-color flows exactly like SC3's RSH'A, & the sound Sig makes times with RSH'A] stance trasition from SC3.
Btw, during 5:22, Patroklos get knocked two times, the 1st looks from 66K then the 2nd is from RSH'A.
I just check it again, Im still sure, & I'm really hoping that Patroklos got hit by 66K 1st, because it can mean that Sig might have 66[K] into RSH which would time with how quickly RSH'A came out.
66[K] into RSH could be awesome to improve Sig's CQC, because if blocked, from RSH Sig has the longest back step into SSH to make rival's quick poke reaction to whiff then punish with SSH'K, back-out with SSH'A+B, or whatever new is in.
If not, then SC3's RSH'A could be the new 66A or 33_99A which would be nice to have it that available :P