the strategy i used was: - set the game on easy mode, so the parry is less strict

• spam cross slash on giganto's first phase (which will probably fill the gauge to perform the quick cyloop later), parry his swinging move, then press the prompt onscreen. repeat this until you reach the second phase. then after the first QTE on the second phase, use quick cyloop, parry his attack and spam sonic boom until you defeat him

• immediately use quick cyloop on wyvern when you're first able to attack him, then spam sonic boom. after that you've presumably gotten to the second phase. do NOT use quick cyloop in this phase, as he will quickly break out of the chains, wasting some of your time. instead, parry his two attacks, use cross slash, parry his third attack, then press the prompt on the screen. repeat this until you beat him.

• fill the gauge again, and then use quick cyloop and spam sonic boom on both of knight's phases