I have created a 2nd version of the build that shows what it looks like without the reaping arc relic and the rare conduit. For leveling purposes it is better to look at this build, it reflects better how the grim reaper is actually played going from 1-100.
So currently it fights with physical skills and the devotion has a small change to include assassin mark. This build is currently ~SR60 keeping all other items the same. I expect it will jump up at least 10 levels with the current outstanding patch changes only requiring to switch back to the old devotion build.
reaping arc is swapped for blade arc skill and the conduit is swapped for Mogara pendant, A forcewave build with shambler heart is also an option but that amulet doesn’t give +1 to soldier and the build is very skillpoint hungry. A 3rd option would be the death watcher pendant but then you have to join kymon’s chosen as the grim reaper.
blight fiend is swapped for skeletal servant
harbinger of souls is swapped for menhir’s bulwark
reap spirit is swapped for blitz, this may seem odd but gives back the -DA from the blightfiend and I actually like the gameplay more this way.