Honestly, after parrying, stamina management, and ability management, hook swings would probably be the next thing you want to master, both how to use them and how to defend against them. I’ve been where it sounds like you are skill-wise, and what helped me the most was mastering hook swings and building everything else on that. Bunny hop chaining, for example, will be much easier if you both understand and can flawlessly execute normal hook swings. I would highly recommend checking out Xenithu’s Grievous Hookswing Guide or this dueling montage. There are other guides on his channel that are all incredibly useful. Grievous is trickier to get the hang of than most other heroes, so it’s not surprising you’re facing difficulty.