This is the curse that Nicodemus tried to kill Harry with in Death Masks, but Shiro took Harry's place. From my understanding, this curse is a more advanced and deadly version of an entropy curse (a curse that kills by coincidence). Nicodemus is able to cast this curse once a year (maybe refreshing around Easter, the anniversary of Barabbas's freedom, and Jesus's condemnation?) as long as he possesses the nose. Since Harry is obviously a thorn in Nicodemus's side, why hasn't he tried to use the curse on Harry again?

My only guess is that the curse can only be targeted at someone once, meaning that Harry is protected from the curse. However, those around Harry are still vulnerable. Who recently annoyed Nicodemus and whose death would cause Harry a lot of pain? Murphy. I think Nicodemus sent the Barrabus curse to kill Murphy, and the curse used Rudolph's poor trigger discipline as a weapon. When Harry finds this out, he will go berserk and hunt Nicodemus down.

Doubtless there had been rumours to this effect for years before he gained the knowledge.

Due to the irregular nature of Harry's apprenticeship, it could be that most or part of the Council don't know what he knows. Eb might have kept the information to himself or just to his friends.

What about the Barabbus Curse? If I remember correctly, the curse was first seen in DM has the power to kill one individual each year via an entropy curse (a curse that kills using accidents and coincidence). This could be how Murphy actually died. I'm sure Nick was angry at Murphy for standing up to him like she did, and this could be a way to get back at both Harry and Murphy.

Can Lara even feed on Harry? In PT, he burned Lara, showing everyone that he was in love with Murphy. If Harry doesn't do anything with another woman (which is likely), he will forever be protected. On the other hand, it might be in Harry's best interest to allow Lara to feed off the Winter Knight's mantle. We know that the mantle makes it harder for him to think at times because it increases his libido. Allowing Lara to feed on the energy might make it easier for Harry to think clearly and become a better wizard and detective.

No matter what, this marriage will make Harry look that much worse to outsiders (especially the white council). Although, he could use this as an opportunity to spy on some opposing faction, aka, pretend to be under Lara's control to infiltrate and gain information on his enemies.

Two, Jim saw too many Road Runner cartoons as a child and wanted to drop an anvil on somebodies head.

Without a doubt dropping an anvil on someone's head was on Jim's writing bucket list.