after the beast dies enemies should start spawning with super steel weapons/armor and before you kill it they could spawn with tichrome gear. these items could also spawn in merchant shops before and after the beast (could be a rarer shop item too).
also i havent checked it yet but the plasma beam should be able to hurt the beast (ezra mentions that plasma could possibly heat up enough to hurt it but plasma guns wont because they are designed to burn at lower temperatures)