I am using Katana which means I cannot use a shield.
I have been upgrading this katana with money and items but is there a better weapon that I could get (which would actually downgrade rush's stat's until I upgraded the new weapon?) ? Or is the katana the best weapon for rush?
I have been reluctant since his stats will go down with a different weapon
Or would it be better to get a small sword and have a shield?
Dual wielding two medium katanas is pretty popular because there is a particularly powerful katana that is relatively easy to create early on.
In retrospect I would have gone with 2-handed swords or katanas, if only because it is not very common among other leaders and would have set Rush apart in that respect. Also later on you get some pretty unique and potent 2-handers.
In short, instant gratification - dual wield medium katanas. Build yourself some Dragonflys straight out of the Namura Mines. Patience - use a 2-hander, and wield the Frostblade and or the Nightbloom when you get them later on.
2handed seems to be a mix of 1h/dual wield in terms of speed/damage dual wield is slow but strong (thank god for critical hits and how frequently they appear) 1h is fast and you can use powergrip skills as well for damage 1h/shield is defensive+fast
Others can probably explain them better than me here but that's the general gist of things.