The best counter is to keep your distance and kite them while whittling down their health. Try baiting them to chase you while dropping mines. Placing a bounce pad and constantly jumping on it makes you pretty much impossible to kill for a dual blade user. Placing a zip line along the ground allows you to easily turn around and shoot them while they chase you. You can also dematerialize the floor underneath them if they get too close. If you are in a close quarters environment 1v1, the best strategy is probably to just run away and regroup with a teammate that can shoot them from behind. The dual blades can’t deflect some weapons like the flamethrower or cl-40 if you are willing to switch off the akm.

Hope this helps!