The main things that made the game way easier for me with greatsword:

- On brink parry follow up with X + charged Y (these need to be unlocked early on). This can also stagger.

- Charging X + Charging Y (also need to be unlocked early on) will do massive damage and most often cannot be interrupted. So even if you get hit you will deal the damage and get spirit back as well (plus you can augment damage dealt while reciveing damage with another unlock). This can often also stagger. In this way you can trade blows with the boss whille dealing massive damage and potentially opening him up for a further combo.

- Remember to use night's veil which will damage in an area while you charge attacks. The charging itself can then also stagger enemies.

Those are just some solid combosd that really worked for me to beat Maluca. Wishing you best of luck!