As you probably know, all melee has two attack modes, a quick attack (left click), and a heavy attack (right click). With the katana the left click is more of a slash, and right click is lunge. I am not positive on damage, but I do know which attack is better for what.
First let’s say you have the chopper perk. Aura, Sparks, Proxy, Kira, Vassili, and Phoenix will all be killed in one shot with the heavy attack. Without chopper the heavy attack will not one shot Vassili or Phoenix. Now, most of the lower health classes are pretty fast, so if they are moving, try timing your attack, or just slashing them twice, as the hitboxes for the heavy attack are pretty iffy.
Now onto medium health classes, like Skyhammer, Arty, Redeye, Sawbonez, Bushwacker, Fletcher, and Nader. All of these mercs will die with two attacks of any kind, so most reliable would be two hit them with two light attacks. However, if you can see that they are at low health, and moving fairly slowly, maybe do a lunge. It all depends on the situation.
Fragger and Rhino are a bit different, as they have a LOT of combinations you could kill them with. I find the easiest way to get Fragger is to do a heavy attack, then finish him with a light attack. Once again, it depends on how fast he is moving, and if he is at full health, or at low health. I believe 3 light attacks will also kill a Fragger. Rhino has the most health in the game, but he is also very slow, which makes him an easy target for two heavy attacks, however, if you don’t have a chopper loadout, that would bring him down to really low health, but not dead, unless he was already weakened, so doing one heavy attack and two light attacks would be better. Also a helpful tip, rhinos try to stay near medics, so try taking out the medic first to prevent healing done to the rhino. Of course, this applies to every situation, usually targeting the medic first will work better.
Another VERY important thing is to remember that you have guns. Very good guns. Always remember to use them. If I messed anything up, forgot something, or you have other tips feel free to share.
