The daggers proc a shield which absorbs 2,000 points of damage. After the shield has absorbed 2,000 points of damage, the visual still remains. During this time, the rogue will take damage. The shield visual disappears after the rogue has taken a total of around 4,000 points of damage.

I thought that this was intended to allow an interval before another shield could be made. But that idea posed 2 problems:
1). In the heat of battle, advancing towards enemies while thinking you still have the shield can be disastrous.
2). The proc rate of the weapon is low (for a weapon that requires you to hit a target in close quarters, and also for a weapon that is held by someone with 4,000 to 6000+ dps).

If the interval is intentional, it may be better to remove the shield visual after the shield has been broken. Instead add some seconds in which a new shield can't be made, but increase the proc rate.

If the extra 2,000 points of damage that needs to be taken to remove the visual is intentional. Please remove the shield visual and just allow damage to be taken, but increase the proc rate.

If the interval is a bug, please fix it

You could be extremely nice and allow the proc to work like the dusk dagger's proc (no need to hit a target), because the rogue may already be dead before the shield appears (more likely a guaranteed death in the mausoleum). In that case you could leave the weapon as it is