I thought about it, and I am wondering if there's a way to put 5 seconds of action in 1 single comic frame, or you need to make 5 frames or 1 for each action. Consider the following fictional excerpt.
He smashed his shield against the guard, and the guard dropped his sword and lost his footing and dropped down the stairs.
Could this description be realistically drawn in 1 single frame, and is it a good idea?
Whether it's a good idea depends on the situation, but it can be done.
For example, consider the panel below where Nightwing's movement is shown in a single panel, by showing him 11 times
You could do something similar with the guard. Have him pushed in one instance, then one instance that loses his sword and starts to fall, then another instance further down the stairs.
(Copied from here)
You can show the guard stumbling back towards the stairs, a sword dropping from their open hand and your protagonist with his shield held in a striking position all in one panel. Maybe add a few action lines. The reader can put it all together from there.
Check how Stan Lee, Frank Miller, and Will Eisner would set an action scene. I think you will get a lot of ideas.
Elaborating on what Kinro said, if you hit someone with a shield, it may continue its movement after it touched the other person. Stan Lee, for instance, would have drawn the hero twisting his body and shield while the guard flew down the stairs, sword still in the air but away from his grasp. Of course the pose would be carefully chosen to indicate energy.
Will Eisner wrote an entire book on Sequential Art (he did not like the term "Comics") based on the class he taught at the NYC School of Visual Arts. The part about describing action, intent, and mood using just art is very good.
