Correct. END's power is not god slaying magic. It's a power that is stronger than that of a god. It has no properties that is inherently effective against a god or time manipulation. It's not even proven to be enough to beat Zeref, let alone kill him. It's just stronger than Chronos.I am not saying it is god slayer magic, it is simply put a power that surpasses the power of a god. I know that even Cheria was still effected by age seal, but god slayer magic like other slayer Magics just makes the user immune to respective elemental based abilities and makes their attacks more effective against gods. While Mira at top condition could not even harm Zilconis, yet a tired out Wendy caused the most damage, it is a means of what can effect others
Though you have to realize that the two have same origins from a god and how to correlate to Natsu who is described to “surpass the power of a god” and how it means. And no, he was not described to burn Mari’s magic, just as END can move in stopped time. With Ingeel’s magic is because he was in the afterlife, not because it was powerful, otherwise, what would be the point of END since they met before
Igneel's magic was able to kill Zeref because it was powerful. That was why Zeref wanted Natsu to be trained in the first place. So Natsu could potentially grow to be as strong as Igneel and kill him. The line where Zeref said "power of the dying" doesn't mean much. If all it took was magic power from a dead guy, then anybody who has magic that once belonged to a dead person could kill Zeref. God Serena could eat someone's magic then kill them, and he too would have the power of the dead. Gray with Silver's power is the power of a dead guy. Literally every 2nd, 3rd, or 5th generation dragon slayer would have the power of the dead. None of these guys stand a realistic chance of killing Zeref. A greater emphasis was placed on the strength behind Igneel's power.