i just use unreal engine 4 for a week and i watch the official tutorial in youtube(20video),it teach me how to punch while walking (only use upperbody) by using the (Layered blend per bone) in AnimationBP
If I understand you right you want to make your slot affecting the legs… you counld place the slot to the base pose or make 2 new layers for the left and right leg. And btw where you got the punch anims from I could need them ^^.