I usually place mines on the ground, then when he steps on them, he should expose his heart. When that happens, use your grenade laucher and magnum.

Rinse and repeat.

If you are playing as Cris, after you stun wesker and he goes into his whirlwind defense/attack run up behind him (be careful one hit from his spin sends you into the lava) and a button prompt will appear. execute the correct button push to start a cut scene leading to the beginning of weskers demise. Rocket launcher in the weak spot is the quickest. If you are playing on amatuer or normal you can beat him by grabbing him from behind when the button prompt appears. On veteran you have to have your health up when you grab him because being on wesker's back drains your health.

I beat him by, after pushing boulder i kept shooting him in the head and back (when i saw weak spot) while he walked towards Sheava (i think that how u spell it) hanging from the cliff and dodging things he threw at me until she crossed the boulder then I shot him in head and weak spots when I saw them until a little bit after he starts spinning those tentacle like things if he isn't already, then ran up to the top of the cliff-like-place and a cut-scene kicked in where he jumps up there too and yells "Chriiiiiis" or something like that then just shoot the weak spot until he covers it up and shoot him in head when he raises his arm up for a while, and reload and heal when he makes those things come out of the ground and spin around him. That's if you can't get behind him or other ways don't work because that is a long (fun) way to do it and better if you have infinate ammo in one of your guns. (I use L. Hawk or the "Hand Cannon")

that really giant s&w 500 magnum makes pretty quick work of him, once fully upgraded.

also, as people are fond of writing on some other forums, "infinite rocket launcher, the end."

quote Ded Valve

You need to beat the game in order to obtain the IRL

yeah, i guess you do, don't you.

that's why i played amateur first instead of veteran...