I am experiencing the same bug with my Necro.
In Deathshroud everything works fine as you expect it to do, but in Reapershrout the weapons/sigils of the second set lose their effects. Its a pity, because the current state of the condition Necromancer is quite good and its a welcomed class in Fractals and Raids. As a Necro main it is the first time in the game, that i can play my beloved first character. The only thing that bothers me is now, that i have to arrange my dps-rotation around this bug. You always have to consider the dps loss when you do more cc by using your Shrout after your warhorn. And that in a rather complicated dps-rotation with some hidden cds and sigil-procs.
I hope this issue can be addressed in the near future to let us enjoy our Necro even more.