When he attacks you when you are going round the ruins, use your knife. Only shoot him when you ahve no other options. Saving your ammo will be helpful for the next chapter. When he transforms his arm. Shoot him in the leg with either the Broken Butterfly or the Killer7 (depends on which one you have) or the Striker/Riot Gun/Shotgun (depending on which one you have) if you don't have a Magnum. Shoot him in the leg until he falls down, dropping his guard leaving you a few seconds to get at his upper body. Shoot him with your Magnum or knife him if you want to save ammo. Repeat. Most of his attacks can be dodged, so keep your fingers on the dodge buttons. Also pack a few recovery items (Green Herbs, First Aid Sprays, etc).
I'm finished here...
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