Issue #4304: [Dawnguard] Dwemer/Dwarven Crossbows can't be used by NPCs
For whatever reason, the animation, action or something, required for an NPC to actually fire a Dwemer Crossbow is missing, or something is flagged on the weapons that prevents their firing by NPCs.
The NPCs will aim, and then relax as if they had just fired, and repeat this until an enemy is within their melee range, but they won't actually USE their crossbow.
They don't seem to have any problem using the default steal crossbows, but for whatever reason, any Dwarven/Dwemer crossbow can't be fired and reloaded.
This goes for the enchanted leveled list crossbows as well, any crossbow that uses that dwarven model seems to be unusable by NPCs.