I've never played a campaign in Eberron, but for some reason I have Dolgrim miniatures and an Eberron Campaign Guide. This is just a quick conversion to 5e.
Dolgrim were created by stitching the flesh of two goblins together. The resulting creature had enough limbs (and remaining brain power) to be something much more dangerous than two underlings.
The fusing process theoretically creates creatures with a single personality, although heroes that have observed a dolgirm claim it often gibbers to itself.
Goblins, orcs, and gnolls, are mean, but dolgrim represent a much more twisted intelligence. Whomever creates them in your campaign world, are clearly deranged. Perhaps they are the experiment of an evil wizard or an insane alchemist. Regardless of their creator, the intelligence that fused the flesh will likely alter the dolgrim's mind in such a way to make them more loyal and steadfast than the average minion.
Replacing the weapons on a dolgrim can create new challenges for your players without changing the challenge rating of the creature. For example, an archer dolgrim could effectively wield and fire two crossbows on a single turn.
You can download a pdf of the stat block here. Let me know what you think.