So after watching the streams:
- I added another state inside the “Run Jump Glide” state machine, called grapple (essentially its just the player with one hand up, rotation while hanging from the grapple point is done by code (could be done by aimoffset?)).
- I will make a melee state that is going to fully override the previous state machine if there is melee action happening (not sure if I am going to do the 1-2-3 hit combo with montage - thats probably the way to go)
- If there is a gun equipped aside the melee weapon and some other exceptions I am just going to blend with the upper body slot
- For any additional stuff I am going to use animation montages (crouch->jump=bigger jump with root motion, crouch+click(melee)->throw axe or whatever…)
What do you think? 
P.S. just noticed you are the guy with supergrid, good job! I am going to buy this soon, hopefully its a good replacement for my awful programmer art modelling and level block-out skills