Well, depends on your view.
If you rarely use sword skills or combos, then I don't think you will miss much by not leveling sword mastery.
But here are a few good skills for sword mastery:
- Castle Shield (when you need that extra phys def boost!)
- Knockdown and Stab (good for annoying the crap out of your opponent)
- Chain Combos (I believe the last chain book is really important as it has dull, bleed, and other status effects[ ?? not sure about that]). Also, they look stylish and cool!
Although you might use your nukes mostly for PVE and PVP but it's up to you.
