reaper attack and two handed weapons
Nope, it’s coded as a hammer. I’m unsure whether On-hit sigils need to be on the active weapon to proc though.
No, it does not matter what weapon you are wielding outside of shroud. Reaper shroud weapon damage uses that of an exotic hammer.
You can test this by equiping an ascended weapon and an exotic weapon before going in shroud, and notice that there is no difference on tooltip damage (or single digit difference in the case that the weapons you are using are, for example, berserker, and the ascended version would have a few extra points of power) to show that weapon quality does not matter.
Now there are two ways of showing it uses hammer values. The first is that when you kill something, it will progress the hammer master achievement or whatever its called that tracks your kills on a weapon. The other way is to take the tooltip damage, and backwards derive the coefficient for that attack using an exotic hammer damage value, and you will see that the coefficient will approximately match the one listed on the wiki.
(edited by chunx.9521)