Snap hand position to a corner on a 2d aim offset?

I have a 2d aim offset with 8 hand positions (4 for edges and 4 for corners, basically a square). I control the position with the mouse movement. Now i can freely move across the 2d aim offset but I would like to make it snap to one of the poses. I thought of using poses individually and depending on the mouse input we would go from one to another, but then the hand just abruptly snaps instead of interpolating from one pose to the other. How should I do it?

I want to achieve something like Mount and Blade where when you move the mouse the character’s arm just snaps to one of the four attacking positions.