Hellfire Guillotine vs Nothung

[Reynhart]

And in 4.0 there will be another tome weapon that's much easier to get than relic.

Easier ? No, because it will probably require raid items to be at the same ilvl.
Shorter ? It depends on how fast you clear the raid.

But if you clear it, then you don't care about the tome weapon, since you'll have access to the raid weapon.