Ninja Gaiden Sigma 2

This is the hardest trophy in the game, in my opinion. Enemies instant kill you with 1 grab, they kill you with 4-5 normal hits and their AI is smarter, meaning they will not be hanging around much waiting for you to attack.

My general advice for the entire game is completely mastering the UT chaining technique, the Izuna Drop, The Guillotine Throw and the Flying Swallow. These are all the moves you will need for killing everything (with the exception of bosses).

UT chaining is by far the most powerful one from the list, I recommend chaining UTs in every fight as long as there is essence around. You will get enough yellow essence from chests, don't worry about absorbing them during fights. The most powerful UTs are the Lunar Staff's 360UT (spin the 360 degrees before holding ), Enma's Fang’s UT and when you get your hands on the weapon, the Tonfa UT. I advise upgrading these weapons to level 3 as soon as you can, they’re extremely useful.

The hardest chapters in the game are 5 and 11 where you control Momiji and Ayane. Momiji and Ayane are weak characters, their UTs don't do nearly as much damage as Ryu's weapons and they're very weak overall. Your best bet is still UT chaining, spamming Guillotine Throws and performing Counter Attacks.

For detailed information on fighting regular bosses and greater fiends, check out RYUUJIN's Boss Guide and Greater Fiends Strategy Guide.

For a complete video walkthrough for Master Ninja difficulty, also check out Kagerasimaru's Master Ninja Story Video Guide.

Good luck!