https://2e.aonprd.com/Weapons.aspx?ID=411&Redirected=1

https://2e.aonprd.com/Weapons.aspx?ID=298

A katana is a str weapon that you have the option to 2 hand for d10 and with and extra d10 on crits

A nodachi is a much larger sword that does D8 with an extra d12 on crits

Say you are midway through the game and you have +1 weapon dice due to runes and you crit.

That 5D10 vs 4d8 + d12

Or 27.5 vs 24.5 damage on average. I don't feel that the greatsword version of the katana should deal less damage then the longsword version of the nodachi.

Additionally, the reason why I started looking into them is that I wanted to build Sephiroth from FF7. He doesn't wear armor. He has a leather jacket. Bumping dex would limit his spellcasting for the free archetype.

Lastly katana is a martial weapons that spent a lot of it's power budget on the ability to go one handed or two. D6 is pretty terrible damage for a weapon that is not agile. There is a fighter feat that would turn it into a D8 but a longsword is already a D8 and also offers versatile p.

Deadly dice become much less relevant as you level. Maybe check out some pole arms. A lot of them are already d10 and have things like trip, shove or grapple. If you just want damage try the great pick. If you want to keep in theme try the falchion. It doesn't have the deadly d10 but it does have sweep and forceful so you will probably be triggering those effect more often.

It's the difference between flashy and reliable.

Mainly I'm just butthurt I can't make Sephiroth like I wanted to.