Has anyone else had a problem where a guy is dashing at you and you do a sword dash to kill him but you end up dead instead?

Most likely Lag, unless he parried with melee (Yes, you can parrie a Sword if you melee at the right time)

Here are factors that play in Surviving a Energy Sword that the guy probably did
-Parried the attack
-Used Armor Lock
-Lag

did anyone of those happen?

being able to parry seems to make sense...or at least explains what happened to me last night when a guy with an energy sword was charging at me and i smacked him and still lived. the end result was still my death, but i was wondering how i even survived the first attack. lag would also make sense.

I didn't know you could parry, thanks I guess that's what happened.