Complex sentence: The two sides engaged in close hand to hand combat, but the Franks were too good, with much of the Byzantine army either killed or taken captive, as the Franks captured a large amount of weaponry and treasure in the aftermath.
Split into simpler sentences: The two sides engaged in close hand to hand combat, with victory falling to the Franks, who killed or captured much of the Byzantine army. The Franks went on to capture a large amount of weaponry and treasure in the aftermath.