In order to snag this trophy, you need to obtain the "No Kill" bonus on 10 ranked battles.
There are two ways to obtain the "No Kill" bonus that I will go over below. Please note that only killing human cyborgs will negate this bonus - other enemies, like gekkos, raptors, wolves, etc. that are not technically "living" do not count against you IF you chop them to little bits. So, I will repeat this again: only killing living enemies count against you.
Also, if you are going for this trophy I would advise playing the game on easy. Why? Because, to be honest, you are going to obtain a mediocre to awful rank for these battles. It is not worth your time to go for the "No Kill" bonus on a difficulty that you actually care about (like Revengeance).
The two ways are as follows:
THE HARD WAY During fights with your standard human cyborg, you can obtain a "No Kill" bonus if you incapacitate the enemy without killing him. For example, hacking off limbs, but leaving the enemy as a living torso will, eventually, cause him to disappear.
Your ordinary, run-of-the-mill cyborgs can be hacked up without an issue. Armored enemies need to turn that nice shade of blue before you can chop off limbs.
If you are going for this method, I suggest playing on Chapter 1 a few times. That first battle is easy enough to get the "No Kill" bonus. Then you can save and start the Chapter over if you wish.
THE EASY WAYGet this trophy:
Finding all the Men in Boxes will give you the HF Wooden Sword. What is so great about the Wooden Sword? With it you will always get the "No Kill" Bonus.
Once again, go to Chapter 1 and just fight everyone. The Wooden Sword will make enemies disappear rather than die or explode, so you will get this done in no time.
Wouldn't the "no Kill" bonus be awesome for the S Rank run on Revegeance difficulty?No, it would not. Don't bother trying it. Seriously, it is not a smart move.
Why?S Ranking battles have about 5 categories that, with most fights, require at least 1k points in order to earn the "S rank". For example, if the time category requires you complete the battle in less than a minute for 1,000 points, then that is what you need to do. Going over the minute mark will reduce the points received, and thus the overall ranking.
The "No Kill" Bonus is worth 1,500 points. Going for the "No Kill" bonus, you completely lose two other categories: Kills (obviously) and Zandatsus. You will also seriously restrict the BP category (as you will leave no holo-chips to pick up). Your only hope then is finding random items during the fight, and picking those up BEFORE you beat everyone else.
You will lose up to 3,000 points in order to get a bonus worth only 1,500. In a few fights you could make up for what you lacked IF you are fast enough, build a decent combo (which isn't always easy with a sword that makes people disappear) and don't get hit ("No Damage" bonus), however with 90% of the fights you are looking at getting an A rank at best.
So, to sum things up, don't think that using the Wooden Sword, and obtaining an extra bonus for battles will make the S Ranking a breeze.
Questions, corrections and neg vote justifications below.