Foremost, they are virtually unlimited. From what has been observed, the power sources use some manner of human emotion as a catalyst and the amount of power they put out is directly proportional to the intensity of that emotion. However, there is a baseline energy output (all humans will, at the very least, cause an amount N of energy to be outputted).
Second, powerful weapons do exist, but ungodly levels of red tape has prevented usage of them. The variable combiner is part of a trans-dimensional storyline that links my own created universe with a friend's universe. In that friend's universe, the world is devastated and war-torn. Resources aren't exactly easy to come by so creating super weapons isn't exactly easy. While the people of my universe could easily send all that stuff over, government red tape disallows it.
Second, powerful weapons do exist, but ungodly levels of red tape has prevented usage of them. The variable combiner is part of a trans-dimensional storyline that links my own created universe with a friend's universe. In that friend's universe, the world is devastated and war-torn. Resources aren't exactly easy to come by so creating super weapons isn't exactly easy. While the people of my universe could easily send all that stuff over, government red tape disallows it.