Tac officers are better suited at range, since they will need to dive in behind cover almost constantly, having no shield or health recharge of their own. For a melee user, I'd suggest an engineer to stock your own shields and make them take less damage.
Right now, using Bathleths serves the purpose of proccing exposes. Since the attacks have virtually no cooldown, and the cast-timer is something like 0.5 or 0.6 seconds, over time it is the most certain way to gain exposes on the enemy. Once that happens, press J, switch to your ranged weapon and use the exploit attack.
The other boon to using bathleths is that the knockdown attack can hit up to 3 targets and has a 50% chance to Hold them for 4.5 seconds. Also spammable.
It is also important to cycle your first and second attack correctly to gain combinations (try it in-game until you figure it out). This makes the damage somewhat better (I also think it's an exploit attack, but I haven't been able to verify).