Bit of advice in addition to my cavalry metaphor.
First of all, avoid charging into a large group of enemies on your own. It would take a very large gap in capabilities to avoid being swarmed and taken down by pure numbers. In this case even if you were always able to take down the Rook in front of you, there are still five other directions that you would receive attacks from.
Secondly, rather than charging directly into the mob you should instead hit the edges. That way you give the enemy much less of a chance to swarm you.
Third thing, when performing fast strikes against a larger force you never engage more than one, maaaaybe two foes before zooming back out again. And they don't need to be kills, the important thing is escaping and avoiding being swarmed by the main group.
Please keep in mind that these are not criticisms of you. I am trying to help you learn and get better at combat.