I mean, I was going to let it go before, but since you chimed in again saying how important it was to get it "fast" and/or "easy", I just wanted to point out that simply purchasing one of the many BtCoE slashing daggers (with red slots to bypass whatever DR you want) is
actually zero time, whereas getting a Nightforge dagger is not because you have to go out of your way to run that stupid quest and also take a non-optimal path inside that stupid quest.
What daggers am I talking about here?
Ancient Vulkoorim Dagger
+5 Dagger (D:1.5[1d6]+5 19-20/x2, Slash, Pierce)
Greater Giant Bane
Giant Slayer
Empty Purple Augment Slot
Empty Red Augment Slot
Bejeweled Letter Opener
+4 Dagger (D:1.5[1d4]+4 17-20/x2, Slash, Pierce)
Spellcasting Implement +12
Keen I
Resonance +60
Devotion +60
Empty Red Augment Slot
Flint
+4 Dagger (D:2[1d6]+4 19-20/x2, Slash, Pierce)
Shocking Burst
Empty Orange Augment Slot
Empty Red Augment Slot
Guardian of the Liturgy
+5 Dagger (D:[1d10]+5 19-20/x2, Slash, Pierce)
Bleed
Heartseeker IV
Empty Red Augment Slot
Tenebrous Stiletto
+4 Dagger (D:1.25[1d4]+4 19-20/x2, Slash, Pierce, Adamantine)
Ghost Touch
Deception
Adamantine
Hide +11
Empty Red Augment Slot
Threnalian War Dagger
+5 Dagger (D:1.5[1d6]+5 19-20/x2, Slash, Pierce)
Empty Red Augment Slot
Empty Orange Augment Slot
And while I'm pushing up my glasses here, it is the adamantine property of the nightforge dagger that bypassed the DR of those mummies you used it on. (Not the slashing.)
(But in case it needs to be said, yes you are correct that it is a good weapon and a good value. I have used it.)