Sorry, I haven't had a chance to reply back to your comments been a little occupied.
B
1) You need to give the unit a passive ability (like AbilityIncendiaryShells) that fires a 'buff' every time the weapon is fired.
2) You need a buff placed on the target that spawns damage to targets in range (like BuffClusterWarheadsSpawnDamage)
3) You need a buff called by the spawn damage buff that actually hurts the individual ships by doing damage (Like BuffClusterWarheadsDoDamage)
I gave this ability to my improved krosov frigates, who have nuclear missiles that do splash damage to nearby ships.
Good luck.
So your saying that it has to an ability ? I thought the javalin units were suppose to damage near by units.
Don't think they use any abilities, looked over there code but I think i may have missed somthing I will check again.