You could just make it not have a melee attack, since that would be unique in itself. Fire Assault actually only has 1. Glue Arrow would be a suitable power (similar to Thorntrops). If you really need a PBAoE, have the arrows shoot straight upwards.
If there aren't any melee attacks then they may as well just proliferate all the Blast sets that are very unlikely to get a melee counterpart, like Dual Pistols, Archery, Beam Rifles and Sonic Blast. Then after that they may as well do the same with melee sets like Martial Arts, Titan Weapons and Staff Fighting.
I wouldn't play a weapon set defender or corruptor with any active secondaries. FF, Sonics, and Ice are fine but anything where I have to sit and watch the pull the weapon out animation a dozen times each fight would be unbearable to me. How often is the target going to be dead by team fire by the time you pull the weapon out and shoot it? Often enough to be frustrating.
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