You can't expect every obscure piece of fanon to be documented. Especially old stuff that newer people (like me) have never heard of.
Also: Why would the Gargant be there if its not released? If INFSCP released the model, I'd be glad to make a page for it. Otherwise, it may as well not exist.
Also, you are dead wrong on Shivan weapons doing less damage per second. An LRed outdamages even the BFGreen. Look at the weapon comparison table's "sustained damage per second", which is the one that really counts.The only case where a shivan beam deals less damage per second is the SRed being slightly weaker than the SVas (which is a destroyer-mounted weapon).