We had this discussion a few nights ago in the ShoutBox. Koloktos is based on the Buddhist god, Asura. Asura is depicted as a six-armed, three-faced deity. This also works with the Buddhist theme of the Ancient Cistern - the three levels representing Hell, the earth, and the heavens above. Hell's design is based on the Buddhist story, "The Spider's Thread," in which Buddha gives a man in Hell a lifeline via a spider's thread. As he climbs, he sees the other sinners are climbing. He yells at them to let go, for fear of it snapping, and as he shouts at them, it snaps.
Vishnu has four arms in most depictions, by the way. One of the few examples is Krishna, who has two arms, on account of him being in a human form.
EDIT: Vishnu also never carries swords of any sort. Shiva the Destroyer occasionally has swords, but never in all of its (Shiva, and most Hindu gods are not gendered) hands are swords.