How can I avoid making attacks that drain my own life?

There is a certain defensive attacks that Tallion does that makes him hit the ground (Elven Light) that makes pushing back every enemy nearby but it drain your own lifebar; I just want to know how to do it and avoid doing it because its make you so vulnerable to captain attacks

The skill you're referring to is the Elven Light. It's the second wraith skill you can learn. You press X + A (or Square + X on PS4) to do the attack when you have enough might.

Elven Light

You probably have some gear equipped that is causing it to drain your health when you are using it. You can drain your own health to be able to perform a skill that requires might, even when you don't have enough.

This is the set bonus of the Vendetta legendary set. This is typically found when completing online vendetta missions. Perhaps you have them equipped?

Vendetta legendary set

Remove some or all of the equipment so that the set bonus doesn't take effect. Then even if you accidentally press the buttons, it won't do the skill and you don't drain your health, it just does nothing.