I would think that in terms of weapon damage no difference, but... When it come to taking damage, if you are 29 and 3/4 rather than only just 29 you must have a raid piece or iron banner piece, as well as an increased light stat, the other stats on that gear are higher, so your total defence number will be therefore higher. Based on the fact these numbers are over 1000 and were probably talking 50-100 difference max it will be less than 10% reduction but it's something. I reckon this equates to no increased weapon damage, but the ability to take a tiny bit more, which may be enough to take one more bullet in iron banner or pve which might save your life ;)