I was reading up on the Elder Pain Omega and the NA PSO2 Wiki says that it's Potential "absorbs damage inflicted as HP". Would that essentially be the same healing ability as the Potential on the Lightning Espada, just with it working on all enemies?

Correct; however, something to keep in mind is that unlike Lightning Espada, Elder Pain Omega has no damage multiplier, meaning that other Swords with similar MEL-Pwr are significantly stronger. In fact, despite having almost 150 less MEL-Pwr, an Atlas Farder with no damage-based SGAs is almost on par with it and you can put Lifesteal on it and further upgrade it.

Ok. Thanks.

EPO's lifesteal is uncapped though which makes it a fantastic weapon and why until 14* cancel registration passes were out it hovered around 100-150m on ship 1. One auto attack = fully heal your entire pool of HP.