NINJA GAIDEN II

Volf, in my opinion, is quite literally one of the easiest bosses in the entire game. Unlike other bosses, like Alexei, who are fast and can be difficult to predict, I found that he telegraphs his movements quite often and is simple to dodge.
(This guide presumes that you know the basic techniques of the game, such as guarding, and dashing.)

Basically what you'll want to do is put some distance between you and Volf. Stay at a reasonable distance and stand still for a second.That's right, just stand there trust me.
Now, Volf's AI is programmed to only have 2 main means of attack when fighting at range. A projectile, and a Dash/tackle. His projectile involves creating a shock wave and is really easy to spot. He'll perform a wide sweeping motion with his scythe, and you'll see the ground explode toward you, so if you see him about to use it start circling around him using a combination of Dashes and Jumps, Dash>Jump>land>Immediately (It's also a wise Idea to constantly be holding down the trigger to block anything that may graze you.) Repeat. When he's finished with it just stand still out of his range again for a moment. He may throw quite a few of these before doing what we want, so have patience.

Now comes the slightly tricky part.

Remember that Tackle/Dash attack I mentioned? In between throwing projectiles Volf will some times drop his arms and roar, this is the signal that he is about to charge.(He also gains an aura around his body as a tell sign) Stand perfectly still and wait for him come charging toward you, then when he is right about to strike you, simply perform a dash slightly to the left or right of him. Don't worry if it seems like you're about to touch him or run right into him, if you time it properly you will take no damage whatsoever. The only real flaw with this method is that if you mess up the timing, you take a pretty hefty chunk of damage.
It may take you several tries to perfect this timing, but remember that a large part of Ninja Gaiden is trial,error, and practice. Keep trying and you'll find the right timing trust me.
Right after that successful dodge he is wide open to be cut down using any weapon you like. I personally like to use X>X>Y on the Lunar Staff because it's very quick plus deals high damage, but you may use whatever you feel comfortable with. Just don't get too carried away.
Simply repeat this process until he dies.

This method has been formulated, tested, and used by me personally to perfect Volf on every difficulty including Master Ninja. If you have any questions, gripes, or helpful additions feel free to post them in the comments or PM me. This was written completely based off of memory, and I plan on updating it further If need be, when I play through again for the weapon based achievements.
Good luck

Volf is fairly simple to defeat with the Lunar Staff, the completely safe no-damage route for use on any difficulty is to back away from him, Charge a 360 *rotate analog stick in a circle* ET/UT, wait for him to charge at you, and when he gets close enough *warning - volf moves faster than you would think sometimes* let loose. If your playing on acolyte/warrior it should knock of a fairly large chunk of his health.

After that back away and repeat the process.

*credit for strategy goes to Reim*