Heavy attack is better on every level. More damage, you can’t be staggered, seemingly equal odds if not better of applying status effects.
I’d suggest that light attacks be made more attractive with one or several following features.
- Increase speed of fast attacks even more.
- Remove stamina cost of light swings
- Half stamina cost of light swings.
- Light swings might even refund stamina in a new grit or agility perk?