so, your oppenent whiffed, and now they are going to cancel
You have a few options
A: do nothing (not completely awful, as then you have the maximum amount of time to react to whatever bull they might throw out after the cancel
B: Use a REALLY fast move to basically cancel out all their options (IIRC, you cant guard or dodge after a whiff cancel, so very fast moves (say, cowboys pommel) can make literally every possible move unsafe and guarentee a hit)
C:Play 'whiff cancel chicken' (Where you just keep whipping out moves and cancelling them until one of you cracks or runs out of burst)
At least, those are the options that go through my head, whiff cancelling makes the game special in my mind, and the entire thing becomes a very tense rock paper scissors situation.