The 'newer' weapon crystals and the Mental Bane tech need to all be Delay Adjusted, like the old crystals were, and like Romp, Pierce, Gale spelltechs currently are.
Delay adjustment means that the added damage from the weapon crystal was the same, over time, regardless of the weapon delay. So a monk with 20 delay handwraps using a 5% chance for 100-120 extra blight damage crystal would do the same damage over time from the blight weapon crystal as a warrior with a 40 delay axe.
The older weapon crystals properly delay adjust by modifying the % chance to go off (multiplies the %chance times wpn delay/20). So that the 5% chance crystal in 20 delay (the fastest delay weapon) handwraps has a 5*(20/20) = 5% chance to go off, or in a 40 delay axe has 5*(40/20) a 10% chance to go off. Since the monk hits twice as often as the axe, the crystal's %chance effect is increased in the higher delay weapon so that over time the damage contributed by the crystal is the same for both situations.
This delay adjustment also applies to spell techs with %chance effects like Romp, Pierce, Gale, and should also apply to Mental Bane (which is not currently delay adjusted, and shows a flat 10% chance that doesn't scale up with slower delay spells). For spells use the spell delay for the adjustment calculation.
I can give specific names of crystals that do delay adjust and ones that do not if needed. Off the top of my head, the Veteran Dark Garnet weapon crystal does delay adjust, so does Icy Beveled Stone. Any of the newer (well, by now they've been around awhile) weapon crystals do not delay adjust. Dim, Pale, Glowing, Bright, Shining, Radiant weapon crystals with % chance effects should delay adjust their %chance, which is all of them save the Dim Crystal of Might.