Although Raste and Bringer can both OHKO any unit within range (Raste has no restrictions, however), the main difference between them is that Bringer works only for himself, while Raste works for you. The other difference that affects neither unit's abilities is that Raste is returnable. Stat wise, Bringer is able to hit first, heal from the previous turn, and kill off a unit 95% of the time. The other five percent is when the unit has massive HP for their level or massive DF. Either way, Bringer kills. Later in a turn, you have Raste. Before a single attack is thrown, Raste ups the MAX HP of all friendly preists by 20, and his action for 2 SP OHKOs, and then HEALS EVERY UNIT. No matter the type. He can heal near infinite really. Either way, when facing them, both units are tough to allow to live and can kill anything you have within range. That is not really something you want to deal with.
When facing Bringer, I found, usually, it is much easier to crush him with Grims or a rush, but with Raste, I'd either have to return him or Grimspam him. Rushes don't work since the priests just rush as well. Especially for cheaper SP costs. With Bringer, after a set, you usually need to wait since you only gain 1 SP a turn after using his skill. So, sometimes, when you need him for desperation, he comes out alone. Raste, on the other hand, is usually played behind some tanks. 1-on-1, Bringer will always win because he moves first. However, in a real battle setting, Raste will beat Bringer because Raste only needs ONE (1) unit in front of him to sac to the Dragon Slayer before he kills the Slayer himself. Raste OP? I don't think so. He's too slow. A ranged attacked can kill him if necessary. And he only affcts HP, not MAX HP. Maybe he could use some tweaking, maybe, but I think he's currently balanced. Bringer OP? Also no. He moves first, leaving him open to attacks fo the rest of the turn. Plus, most Grims can attack him while he's weak at the start of a turn. His healing and high AGI can only do him so much. Raste is the one who can take a hit, then move and heal EVERYONE. I'll say it again. Bringer works for himself. Raste works for everyone.
Paper is sorta OP... Scissors are getting sharper. ~Rock
"Based off of Alteil Errata 5/27/11."