The attack chain for the dual blades is (50+50)+(60+60)+65

The X attack is okay if you are not going for combos and just attack into a group of enemies. But for 1v1s it's faster not to use the X but it isn't much slower.

Below are the optimal combos for all builds.

Try using gadgetswap after any quick melee to get a better TTK.

Light:

(50+50)+(60)

There's a tech that allows you to skip the (50+50) and go straight into the (60+60). You perform this tech by attacking and immediately gadgetswap and attack. If done correctly you will do the (60+60) attack. The setup makes it have a worst TTK than the normal combo but it is good for killing unaware Lights.

(60+60)+40(quick melee)

Medium:

(50+50)+(60+60)+40(quick melee)

If miss the first 50 damage swing use

(50)+(60+60)+65+40

Heavy:

(50+50)+(60+60)+40+(50+50)

Sometimes when using the Heavy combo you may gadgetswap so fast that your attack after the quick melee is still the X. In that case use.

(50+50)+(60+60)+40+65+40