Shard bombs are currently in a fairly poor place, and see very little use for a number of reasons.
1. It takes too long to start dealing damage. Fuse time is 2 seconds for inner shard explosion, and 2 seconds for outer shards explosions.
2. You must hit more than 1 shard to deal decent damage.
3. Knockback feels random, as these bombs are essentially 8 mini bombs exploding at the same time, causing knockback in different directions
4. They feel frustrating and inconsistent to use due to this "randomness" in addition to the fact that you need to hit more than 1 shard.
5. Small enemies are difficult to hit, especially since most of them are also fast. You have to predict where they will be 4 seconds in advance, and even then you probably wont hit more than 1 shard. Meaning mediocre damage.
6. Singular enemies are difficult to hit. Everyone knows bombs are best when vs groups, but shards are very good at killing all but one or two of a group of enemies. Meaning that every situation ends in a frustrating chase between your shard bombs that explode 4 seconds later and an enemy. Ever chase a gremlin mender that will never stop dodging with a Dark Retribution, or a Mortafire that will never stop turning without some sort of crowd control? That's what almost every situation turns to with shard bombs.
Simple Buffs
I don't think that all these buffs need to be applied to make a "fixed" shard bomb, I'm simply listing a number of buffs I believe would help
̶-̶O̶u̶t̶e̶r̶ ̶s̶h̶a̶r̶d̶s̶ ̶e̶x̶p̶l̶o̶d̶e̶ ̶f̶a̶s̶t̶e̶r̶ ̶t̶h̶a̶n̶ ̶t̶h̶e̶ ̶i̶n̶n̶e̶r̶ ̶s̶h̶a̶r̶d̶ ̶o̶f̶ ̶a̶ ̶n̶e̶x̶t̶ ̶s̶h̶a̶r̶d̶ ̶b̶o̶m̶b̶:̶ ̶A̶l̶l̶o̶w̶s̶ ̶e̶a̶s̶i̶e̶r̶ ̶c̶h̶a̶i̶n̶i̶n̶g̶.̶ ̶R̶e̶a̶l̶l̶y̶ ̶a̶n̶y̶ ̶d̶e̶c̶r̶e̶a̶s̶e̶ ̶i̶n̶ ̶f̶u̶s̶e̶ ̶t̶i̶m̶e̶ ̶f̶o̶r̶ ̶t̶h̶e̶ ̶o̶u̶t̶e̶r̶ ̶s̶h̶a̶r̶d̶s̶ ̶w̶o̶u̶l̶d̶ ̶h̶e̶l̶p̶,̶ ̶b̶u̶t̶ ̶I̶ ̶t̶h̶i̶n̶k̶ ̶t̶h̶i̶s̶ ̶i̶s̶ ̶t̶h̶e̶ ̶b̶a̶r̶e̶ ̶m̶i̶n̶i̶m̶u̶m̶.̶ [Too similar to the final point in this section]
-Increase blast radius of outer shards: Better consistency for 1. hitting shards on fast, small enemies, 2. hitting more shards on slower enemies.
-Increase damage of shards: Won't have to consistently hit 2 shards if you are dealing nitro damage per shard or something.
-Give the inner shard a larger radius: Makes chasing easier, and hitting 2+ shards easier (although the inner shard deals slightly less damage)
-Make inner shard explode immediately upon bomb placement: Makes time for outer shards to explode similar to the rest of the bombs in the game. Also makes shard bombs fill a niche with the inner shard (breaking blocks/hitting close switches) that other bombs are bad at because of their fuse time.
-Give outer shards a massively reduced fuse time. Gives the inner shard an actual purpose so we can knock enemies into the outer shards without enemies being able to just walk out of their radius.
Reworks
-Instead of exploding into 8 outer shards in all directions, explode into 3 shards grouped in the direction faced. Makes hitting a lot of shards easy. Makes it great at dealing with large, slow moving enemies (3 shards ~600 damage), and gives the pulsar game plan to shards for groups of enemies(push enemies into corner/wall for massive damage)
-Shard bombs in a line. Upon placing a shard bomb, 4 shards are placed in the direction faced. Each shard explosion knocks an enemy back into the next in line, and they explode in quick succession.
-Shard bombs as blast network bombs. Upon placing shard bomb, 13 shards are placed, creating a plus sign (1 shard in center, 3 in each cardinal direction). Each shard explosion knocks an enemy back into the next in line, and they explode in quick succession. I don't like this as much as the previous as it seems more difficult to use consistently, but if for some reason there is a problem with bomb placement being dependent on direction faced, this is an alternative.
-Shard bomb pinball. Change the outer shards similar to Tortogun shards, bouncing enemies around inside, dealing damage. Makes shards really strong if in the middle of a lot of enemies, like maybe a vortex, as they would be pushing each other into shards quickly. Can still explode at the end, or not if that makes it easier to balance.
-Outer shards explode once in range of mobs, essentially a proximity bomb. Now you don't have to wait do deal damage, and encourages teamplay as party can push mobs into more damage.
-The obvious reversion to old shard bombs that people have been asking for since 2013. I honestly like the other rework ideas better because I think they're cool, but I, like many, would still be ecstatic for this change.
Just throwing out some ideas that may make shard bombs not be seen as one of the least useful/most harmful weapons in the game.
If necessary I can edit the post to qualify my reasoning for any point made, but it felt pretty self explanatory to me.
If anything, shard bombs have the most consistent damage out of all the bombs, behind Dark Retribution. They have one of the fastest charge times, they don't slow you down while charging, the fact that they provide 2 separate explosions gives it more "consistent" damage.
The knockback is clearly based on where the enemy is to an individual shard, and being hit by two will bop them a bit more from the shard explosions.
If you'd want to think of it this way, it requires mild "skill" to watch where things are being knocked back and where they will be knocked back after, and the direction they're walking to bait, then to plant the next bomb appropriately to consistently chain hits. The fast charge speed and movement speed shard bombs have makes this easier.
The status shard bombs are pretty decent at inflicting their status effects, making them pretty viable and making it easier to get hits or multiple hits on an enemy.
As per usual, many "utility" or "bomb" weapons are harder to use in squads due to aggression being across all players in a squad instead of the individual weapon user. It's harder to bait and trail enemies while in a squad.
At the cost of damage and range, shard bombs give in consistency and speed. They're just overshadowed by DBB and Dark Retribution. As far as I see, players just follow others or "veteran" players that claim the bombs are bad, or are too stuck up with nostalgia with how busted and clunky the "old" shard bombs were.
They don't provide much knockback, so outside of the status-based shard bombs, they don't grant much utility. Anything that isn't mist, dbb, or bab usually fall off in worth while in a squad.
I have never used DBB or the default Blast Bomb line, so I'm unsure on how fast these bombs charge and how much of a movement penalty, if any, they give while charging. Criticism to my post would be appreciated relating to my lack of knowledge of these two bombs.