as a side note - that entire storyline makes no sense.
1. Apocalypse was supposed to be in his rejuvenation chamber at the time, since it was before X-cutioner's song but after his destruction in X-factor.
2. He planned for "years" to develop a drug to weaken Namor, but didn't realize what's common knowledge TO THE ENTIRE PLANET - Namor is a mutant with different biological properties (the fact that Namor isn't blue like the rest of the Atlanteans should have been a cue).
3. If years of planning were about to go to waste, and he's so mighty, he would have just grabbed Namor and subdued him himself. What, you think Thanos would have just split? In fact, if he's so mighty, why the need to spend YEARS working on a way to drug Namor in the first place?
4. Years of planning and all kinds of celestial technology and he can't build something to contain a CL100 character?
5. Why is he on the ocean floor, in Namor's native element???
6. Why would he say, "one day, you will be mine!!!", then five seconds later order his servant to kill him?
7. Why is he so pressed to leave because of a little water? Oh, because of the tons of pressure that would crush him? So then....
8. ....how is transforming into a submarine at the end of the issue to escape possible (not shown in these scans)? It's still his body If he could have transformed his body into a form able to survive in the deep ocean, why was he in such a rush to escape?
By the way, in HoM, it's both the same Namor and the same Apoc. It's been made clear that it's not an alternate reality - it's 616, and it's clear that the only thing different about these characters is their memories.
Also, Apoc didn't beat Namor. Namor knocked Apoc into the ocean, then Apoc knocked Namor out of the ocean. It was a shot for shot tie. Namor was put on ice by Iceman while in the air.
Both fights mean nothing more than showing that they're on comparable levels. And that's an assessment I can agree with. Apoc is NOT a skyfather, and should be solidly competitive against low end herald characters like Namor and Hulk. Nothing more, as his performance against Black Bolt should prove.