Hey, just wondering about Dark Heresy Ascension vs Deathwatch... Psykers in Ascension can get up to I Think Unnatural WP x4...
Dont Space Marines get that? I didnt find it in the books...

and while we are at it, a lot of Ascension characters have unnatural traits (x2 x3 x4) in their ranks where is it at when we are talking about the superhuman Space Marines?

On account of Ascension being stupid, I believe they chose to disregard much of Ascension when fashioning Deathwatch (...I'm not even sure when each was released), resulting in a rather large disparity.

If memory serves, Space Marines don't get any Unnatural Characteristics except the ones they start with (which are already ample).

Eh ... The Unnatural advances in Ascension are Primaris Psyker (Willpower), Inquisitor (Willpower), Sage (Intelligence, I think), Magos (Toughness, Intelligence, maybe Strength, don't remember the complete Magos list for sure off hand), Vindicare (Strength, Toughness, and Agility for free). They're mostly Unnatural x2, with the main exceptions being Willpower, and maybe Intelligence; that is, the physical characteristics are x2 and the mental characteristics can go higher. Oh, and if you're a Sororitas there's some cloak you can get to get Unnatural Toughness.

I can definitely believe Astartes Librarians being able to get Unnatural Willpower at some point, and the same for Techmarines getting Unnatural Intelligence. That said ... further improving their Unnatural Strength or Toughness seems unlikely, as does getting Unnatural Agility.

That said, the only RAW ways to get an Unnatural Characteristic is to get sufficiently high quality Cortex Implants, which will give Unnatural Intelligence(x2), or by RAW-theory you could get best quality synth-muscle grafts, although they're not in any of the DW books, though they're in all the other lines, and I think I'd probably say that they wouldn't help an Astartes much. I think that there are also some Chapter-specific Relics that can grant Unnaturals as well.