What I would like to see for bombers is more variety in attack style. Unlike swords and guns, there are no normal attacks for bombs, so there are roughly half as many attack styles for bombs as there are for the other two weapon types. Right now, we have haze bombs, vortexes, shards, blast bombs, and Dark Retribution. That's not a whole lot of variety in mechanics, especially because only blast bombs and Dark Retribution have serious damage potential in most situations. (Fixing shard bombs is another priority, but that's a separate topic.) What I propose are two bombs that would really add some flavor imo:

Claymore-style bomb
Rather than a boring circular blast radius, this bomb would be directional and have a cone-shaped blast zone. It would have roughly the charge time of a Nitronome, no speed penalty and a slightly higher damage to make up for the smaller blast zone. Fuse time would be roughly that of a Nitronome, or slightly longer. The line would start at 2*, with a blast cone about the length of a 5* Nitronome radius and maybe 30 degrees arc (notice this is quite small- 1/6 the area covered by Nitronome!) Higher * levels would widen the radius up to maybe 60 degrees, with a cone length about 3/4 the 5* Nitronome's diameter. There could be two types, one with knockdown, the other with knockback.

Lobbed/launched bomb
This bomb would have an intermediate charge time (maybe a bit faster than haze?), moderate movement penalty (75%) and low fuse time (equivalent to Nitro or slightly faster). The key thing is, upon "setting" the bomb, instead of placing it at your feet, your knight would lob it a pre-set distance, about the radius of a 5* Nitronome give or take; its blast radius would be somewhere between the size of a 3* or 4* haze bomb. You wouldn't be able to adjust this distance, which makes life a bit more exciting as you can't just point and fire. This could also be combined with existing mechanics: for example, a vortex launcher, a status grenade, or good old fashioned anti-personnel blast.