Transition to a proper melee parry/hit react mid-swing(mid animation)?

How is a mid-swing parry or hit react animation done properly? An enemy is swinging a sword at you and you want to block it. There are many places along the enemy sword path that you could overlap you sword to block. How do you keep from snapping into an odd looking parry react animation? Or if you were to strike the enemy body mid-swing, how do you smoothly transition to a good looking hit react from the current position in its swing animation? How do you avoid snapping animations that don’t look like they fit? Thanks in advance