I would be ok with this as long as: A. It receives a 40%-50% damage reduction while firing through the bubble, and B. Firing through the bubble reduces its duration.
[quote]Immobius should be able to shoot out from inside a bubble.[/quote]
IFYP
Fabian Strategy should be buffed, but tying both of the Titan weapons to Defender isn't a good idea.
As a Warlock player, I actually support this idea given the fact both of our Warlock weapons are tied to our class abilities. The Titan gets a nice shotgun that compliments their Super, but then gets a generic Auto Rifle that doesn't really do much in terms of standing out. Fabian Strategy should shoot from a bubble so Immobius can combo with it.
It isn't OP if the requirements for the gun are for the Titan to run Armor of Light like Immobius requires. This way, the Titan can't cheese with Weapons of Light behind projectile shield for ~30 seconds. It simply becomes a normal AR encounter with a brief bonus of deflecting incoming enemy fire - the enemy can always leave the Titan alone. Honestly, if you are engaging a Titan sitting in his/her bubble, you're asking for trouble...