Hey Knuckles,
I received my 1st saber recently and had a similar dilemma to you.
I'm going with a Blood Orange (a colour a bit deeper than Pyrestone Orange I generated from the Emerald driver) look and wanted a fitting deep sound font.
I've uploaded a large number of fonts in the short time I've had the saber and as far as deep and menacing goes
IMHO you can't go wrong with either Dominux Nox, Black Star or Stygian General.
All incorporate a very dark hum and overall menacing clashes. I'm sure some Hybrid of those, coupled maybe with Lord Vanes Vader fonts, would see you right!!!
Myself I'm alternating between Dominux Nox and Sister of Shadows ATM. But on all font sets I throw in Ninja-Jesus' "Epic Music" Lock up (from his Qui -Gon/Obi font) as a 2nd Lock up font, after all, can't beat having a little Duel of The Fates on tap
Good Luck getting the Dark sound you're after m8!!