Blade Kitten

A very simple achievement to nab in the early stages of the story mode, being that the enemies are still very basic and often only require one hit to kill.

This was the first achievement I got, and my secret weapon was basically keeping a keen eye on the surroundings; while it's easy to just run head on into a wave of bad guys spamming the X button, you'd be wise to approach it a little more tactfully than that, to assure your success.

Note when you see the line of sight from enemy weapons, as this usually indicates they're about to unload on you, and if you're unable to avoid contact, make use of your shield using LT.

EDIT: I've also been informed that Darque Nights might be a great level to do this on, and after having another look at it, I certainly see why.
The enemies of the level consist of the highly-damaging, yet slow, melee monsters, I guess known as 'darques'.

And thankfully, their available in large numbers to dispose of. So employ the same tactical approach I've described above, and if you haven't got it already, this should definitely be the level you get it on.

Good luck, it's fairly simple but could frustrate if you act invincible and just storm the place.