Well, I'm not that big on the modern weaponry angle displacing bending angle. I mean, the magical kung fu is a huge part of the fun! Between the devastation brought about by mechs, 'giant robots' and super-weapons, I could see the Avatar making it part of her duties to keep technology from going overboard. With Republic City and ... the ?United Earth Republic? ... presumably pretty well behind her now as well, I could see a four nation treaty happening about it, making the production of weaponry beyond a certain level of destructive capability illegal.
Of course, advanced mecha built for labor or exploration aren't exactly non-dangerous when put to improper use and there's always warmongers and criminals, but active efforts to stop such advancement might keep at least weapon tech a little more restrained.