@_hng_
A nihonto can also have varied hilt lengths. The actual weight of the hilt of either a Japanese sword or a European sword is negligible when it comes to balance in handling, because the weight of the hilt is entirely in your hands (no leverage from it acting as a simple lever). Only when you get to polearm length that they
might become significant (it usually won't, because you'd still want to hold the shaft at the very end). The pommel of a normal battle sword isn't large at all. You actually want to be able to grip the two-handed sword at the pommel with your non-dominant hand. Only swords specialized for mordhau would have significantly bigger and heavier pommels (basically two-handed maces with a blade for a handle). The Viking sword has a large pommel too, but it's meant for supporting a particular grip - it's meant to be placed at the heel of the palm.
The main selling point is the heavier blade
It's only as heavy as a European longsword. If you're looking for something that can actually chop, look for a falchion or an axe. A katana isn't meant for that. While the curvature is a result of forging techniques, it's also a desired shape. For one, it helps with unsheathing as it's meant to be a sidearm. The predecessors of the katana were much more curved, which are better suited for the warrior class who were usually mounted (horse archers basically). Curvature of the sword helped in quick cutting - meaning you cut and the blade would be less likely to get stuck - important for fighting while on a horse. Not saying that the katana is a decent cavalry sword. It's really just a sidearm.
but I think Shadiversity had already explained it fully
Shadiversity himself said that the katana facilitates edge alignment