You can kill Beowulf before he even shoots the feathers at you. However, to avoid the feathers, just save up your DT, and use it when he starts shooting them at you - you can outrun them in DT mode as you run faster, and if they hit you they'll do almost zero damage because you are tougher in DT mode. That's how I deal with it if it comes up.
Other than that, jump up and hit him in the face with an air attack, which stuns him, then get some cheap shots in, and then run away before he smacks you. Taunt him, then when he gets close, jump away to avoid his attacks, use ebony and ivory to stay in the air if necessary, then hit him in the head again and repeat. When he runs around the place, just roll out of his way or jump, and taunt. When he runs to the corner and knocks stuff towards you, just stand back and roll out of the way of them, that's the simplest thing to do. You can also use the rocket launcher to just blow them up before he knocks them at you I think.
