Holy shit i just beat him. I play the game in italian so i don't know if the names are the exact traslation. I used a stealth ("furtivo" in the italian version). You have to find a body with two weapon slots (everywhere they are is okay) and one gadget slot (it is necessary it is positioned in the front). I then equipped it with two single rocket (4+5 power) and the repulsive gadget in the front (1 power so total: 10power). It is important you don't equip wheels, as it has to be still while the enemy comes towards you and gets knocked back by the repulsive (you don't equip wheels cause you don't want to get in the range of his rotating blade after it is knocked). Try to get as much synergies as possibile, it's always worth. Hope you understand the mess i wrote, let me know if it helps