Arcana
Elemental damage
Faster bullets
Larger clip
Less damage per bullet
Knockback
Charge: Weak but has knockback
Nova Driver
Elemental damage
Slower bullets
Smaller clip
More damage per bullet
Ricochet
Charge: Powerful but no knockback
Stats show that both of these guns are to some extent balanced in their stats LD-wise.
What makes Arcana overused in LD and what makes Nova Driver underused in LD?
In most people's eyes, it's a lot easier to hit people with Arcana than Nova because of Arcana's superior bullet speed and size, and not to mention ease of use with a 3 shot clip rather than a 2 shot clip that Nova has. Nova does have the potential to be more damaging and be more tricky (as in using ricochets in tight corridors and such), but you have to work quite a bit harder to actually hit people with it, than Arcana which is much easier. Plus, in general (not just PvP), Nova has a considerably steeper learning curve than Arcana, so it draws more people to the Arcana in the first place.