Do you also think that the default enchantments on the Nightingale Armor suck? And that the already existing mods to improve your armor were too overpowered? Well I did anyway, but because I thought this was the best looking armor in the whole game, I decided to replace the enchantments with some other, better enchantments, especially suitable for assassins. The enchantments are:

Nightingale Boots:
Muffle (didn't replaced this one because I was quite satisfied with the default enchantment).

Nightingale Gloves:
Double Backstab Damage (same enchantment as on the Dark Brotherhood gloves)

Nightingale Armor:
Fortify Stamina (better than the original one, but not overpowered)

Nightingale Hood:
Fortify Archery

The level of the enchantments (except the one on the gloves), depend on your level of the Nightingale Armor, just like the default ones.

I am also working on a Better Nightingale Enchantment for Thieves mod, so if you prefer that one, please stay tuned!