As it stands now, we have shields that are great for great for swordsmen (Dark Thorn Shield) and great for gunslingers (Swiftstrike) but we don't have really good bomb shields. Sure, you could use Grey Owlite, or Skelly, but those are just standard shields. We need a shield that has bonuses for bombs.
My proposition is the Bomb Sack. It wouldn't give traditional bonuses, like Bomb CTR/Damage, but it would offer bomb utility. It's a 3* shield like Swiftstrike, offering about the same amount of defense as Swiftstrike would. When you shield bump, the shield bump would do some amount of damage, so you can finish off enemies with very low health instead of having to charge another bomb.

The shield would also have a completely unique shield bash. Instead of a typical bash, you have a bomb barrage. Activating the shield bash would cause your knight to, after a small windup, toss a volley your equipped bomb in front of them similar to how a Gremlin Demo would (Not the bomb cluster, but tossing a bunch of bombs one at a time). These bombs would have no charge time needed, but it still has fuse. It would also be a cooldown based system, rather than a shield health system (possibly 15 seconds cooldown). This has very obvious benefits for bombers, like being able to inflict mass status or barrage cornered enemies with Big Angry Bombs. If paired with a Shard Bomb, (assuming invinciticks were removed, plugging my old thread here) it would create a massive minefield for the monsters ahead. I don't feel like this would be too overpowered, considering Swords have things like Brandish charges on a much shorter cooldown.

IDEA 2: Reactive Plate (credit to Sir-Pandabear)
The Reactive Plate would be a shield with a special shield bash. Pressing the shield bash button with a fully charged bomb would store it on your shield, and would immediately blow up when your shield is broken. Gives BAB new utility as an emergency escape tool. Maybe he multiple branches to 5*, for status or damage resist.