The Demons are super easy to solo I found with a couple well known pathing spots and tricks available on youtube.
You do not need the Blue Sinew for the bow only for the Ancient Sinew Wrapped Lamina, the BIS quiver.
Good luck! Probably my favourite quest to do in game.
I’m currently done everything on my hunter except the Black Dragon Sinew. Who would have known that Jail Break would be the hardest part!