I've suggested it before and I'll suggest it again...Underwater combat mounts (possibly in the form of vehicles) . Use those to fix the movement issues while developing a new, engaging combat system around those new mounts.I think new underwater combat should be focused on ranged encounters, making the best use of the action camera. Underwater evades are awkward at best, and I think focus should instead be placed on blocks and improved mobility. Another possibility is a mount/vehicle that uses Mirage-style evades instead of dodge rolls.