Editing manequin arms from FirstPerson template

I am using manequin arms from FirstPerson template and I need to change angles of arms in animations, because of using gun with different sizes, but It seems like I need external program for do it. I tried Blender, but I don’t want to learn ■■■■■■■ hundreds of control keys(It’s absolutelly iritating for me to work with it).

So is here any alternative how to simply make/edit animation?