I have created four variations of icon packs for you, all based on the Arthas guitar image you provided. Two of the icon packs are made so that you can use it as a unit (Icon pack 2 and 4) and two are made so that you can use it as an item/ability (Icon pack 1 and 3). I have made the icons so that they have all the borders (BTN, DISBTN, PASBTN, Autocast and DISPASBTN).
Simply download the files, and extract them using WinRAR or any other extraction program that can extract/open up .rar archives.
The pathing for the icons are simple:
I need something more freehand. But so far this one is the best. I dont know why, but this icon is very hard to draw for me. I`ve done some tries, but it`s going slow. So if someone could do it faster, it would be nice ;] Anyway +rep Nerzulll for the best try so far.