I'm playing a similar build on Legendary without a problem. Currently wearing Ancient Shrouded Armor, so that's a 35% Archery boost I think. Backstabs with Bound Daggers. Stand up fights with dual Bound Swords. It's all good. You just need Quiet Casting perk from the Illusion tree.
Yup. With dual Bound Swords. Things are usually dead before it comes down to a melee fight though.
I could see a Nightblade using the Detect spells. Or Aura Whisper.
Your only problem is the fact that conjuring them is noisy thus making sneaking more difficult.
But, as has been said you can use Quiet casting (Illusion perk) to overcome this.
Love your sig. A classic quote from one of the best Sci Fi movies ever made.