Idk, I think the Std Issue and Liberator are some of the thicker sabers. The OD of them is the same as the OD of the thick parts of the prophecy. The prophecy also gets points in the weight category since it is the shortest (other than the initiate) I think the aeon/dominix is probably the slimmest and actually the War Glaive is pretty slender too as massive as it seems - not as light though.
Either way, all of them are pretty slim - I wouldn't worry about it too much. Get the saber that is calling to you!
