It′s INCREDIBLY simple thing to do yourself, but of course it requires a few simple steps. Please it try it out yourself, after all I′m taking the time to post you the instructions - and think about it, after you do it once, you can do similar things to other animations as well!
Summary: all you need to do is to rename the file, and rename one word INSIDE the animation. But for these two steps you need to:
1. Get access to the animation file. For this, you need to extract the whole Oblivion - Meshes.bsa (it′s inside your Oblivion\data folder).
See http://cs.elderscrolls.com/constwiki/index.php/BSA_Unpacker_Tutorial to get that done in a snap. Notice the download link for BSA commander that extracts the bsa for you.
2. Open the animation file. For that you need this tool: http://sourceforge.net/projects/niftools/files/nifskope/1.0.22/nifskope-1.0.22.8329d39-windows.exe/download
Done?
Check the contents of the Oblivion - Meshes.bsa you extracted. The file you are looking to modify is characters\_male\handtohandattackbackpower.kf, double click to open it with Nifscope you just installed.
On the left, you see a "tree view" of the animation data. On the very top, there′s a "name" that says "AttackBackPower". Double click it, to change it to "AttackPower".
Now save the file to some other location, with name "handtohandskill1attackpower.kf". Then copy your new animation replacer to your Oblivion\data\meshes\characters\_male folder (create any missing folders if you need to).
Oblivion will now notice that you have a "replacer" for the apprectice HtH powerattack, and use your file instead. To revert back to original, just delete the file you copied in - Oblivion will use the original one from the bsa again.