That sure is a lot but I stick to my guns when I say thats done through an animation blender that counts every combination of independent body parts animations as a single animation even if the difference between two is nothing other then clenching a fist
e.g. running with a sword in hand
e.g. running with a clenched fist.
the only difference is the arms and hands. This is programmed in and the arms motion is blended onto the character through code. This prevents the animators from having to redo the entire run animation again as 13,000 individual animations would take up quite a lot of the disk space.