Well I actually find how the anime ended kinda well.... I don't really think it's possible. No one can lend another shaman their furyoku. The only way to increase ones furyoku is through death or in a somewhat death like state and there's also the great spirits blessing. I mean in the anime ending they've been fighting Hao for about how many episodes then it just all ends with a slice a kaboom and then everything disappears. I believe that it could have been better really. After all that fighting Hao just dies with one slice.... If only the manga finished it would have been great and Yoh hasn't failed yet. It's just that it didn't truely end. They still had a chance to eliminate Hao while in his coma state.
Beware: Asakura Hao fangirl
Anime is my sole source of joy.