Blade is not a mutant. He doesn't have the X-factor gene present. Namor does. That is why he as well as his cousin and one other Atlantean are considered mutants.
First off I don't enjoy that they are spoiling Second Coming with these teaser images. I do however like where this may be headed. It does bring up new questions.
Will Second Coming have the end result of the X-factor gene occuring again?
Just this question can lead into so much more. This is where knowing your Marvel history comes into play. They have said in the past that the 'mutates' such as Spiderman and the Fantastic Four exhibited potential in their DNA that allowed there mutations to happen. Then there is the whole Earth X thing that revealed the celestials may have done this to Earth and Humans on purpose, which is why the X-factor gene was becoming more prevelant. Is this why the Celestial involvement in the much on hiatus Astonishing X-men book occured and why Magneto and High Evolutionary lobotomized a Celestial?
Are they just again changing what the requirements are to be a mutant?
This is the one that pops up right away. If spiderman wasn't pictured then looking at Lyra and Blade you could go..."oh just people born with powers." But Spidey screws that theory. So are we just going to call anybody with mutated DNA a mutant now so that the mutants don't feel so much like an endagered species? Or is the X-factor gene going to appear in these people's DNA as a result of some sort of "anti-M DAy?"
So each question just leads to more questions. So other than the spoilers, I would say this is successful marketing to get X-fans pumped for sure.