I used Yell and played as a Monk with Guts, Punch Art, Blade grasp (useless in this battle), Two Swords (useless for the first half of the fight), and Move +2. I Yelled until I was getting 6 turns in a row, then stood across the chasm and Earth Slashed every turn to win... then Velius came in, but he got hit by two punches every turn for 120 damage per hit... he didn't last long. Also, having Chakra can help too, since Wiegraf WILL hit you at one point or another... just use it in the middle of a turn chain. The fight isn't hard, just long.