What is the use of longsword pommel strike combo? Everytime I use it, it knocks down the enemy. But I can't hit him while he is down or while he is standing up. So what's the point?

Should I only use it if I plan to escape or make some distance to shoot him with an arrow? It doesn't make much sense though because I just knocked down the guy so the more natural thing to do is try to stab him before he can recover.