Axiom + amber plasm/ trainee/black rose (5pc is essentially 65 stam and mag regen after the constitution buff and both weapon and spell dmg). Tri glyph everything. Use lover mundus. Heavy armor.

Come to think of it, pelinals would be better for nb as they don't have access to both major brutality and sorcery. Mag dk and mag sorcs do.

So pelinial would be best stacking wpn dmg in heavy to get dmg and regen.

A few more thoughts to add. Nightblade has pretty good synergy with a hybrid build (I would say 2nd only to DK). Mark target reduces both an enemy's physical and spell resistance, and sap essence provides both spell and weapon damage.

You'll have a difficult time getting to decent crit chance on both weapon and spell, but that's where the mechanical acuity set comes into play. You will not be able to utilize both light and medium armor passives for crit, and you probably will not have bar space for slotting Inner Light (10% spell crit) and Expert Hunter (10% weapon crit). The best option may be to slot one of the 2, then buff the other type of crit with potions.

For armor weight, heavy is probably the best option for a hybrid in PVP. If you plan to do any damage in PVE you will have to choose either Light or Medium. Personally, I think Medium has slightly better passives, but Light allows the use of Annulment, a powerful damage shield (shuffle is not important for NB since they can get evasion through class skills). Whichever main armor you choose, use 5 pieces of that weight and 1 of each of the other weights. This will give more of all resources through undaunted passives.