Perhaps a katana for bad-assness...

Oh god... you're one of
THOSE people!
*WARNING! WARNING! WARNING! RANT MODE TRIGGERED!*A katana is not some ultra-super-special mega-sword. It's a good weapon for draw-cutting (aka "slicing") through lightly armored opponents, but so is a standard saber, a scimitar, a falchion, or any of a dozen other curved blades. And, just like any of those, it can be stopped cold with a simple wooden shield, something the Japanese never developed, let alone anything approaching proper metal armor, which they never had either.
The simple fact of the matter is that Japan just didn't have the quality or quantity of iron to come up with effective defenses to swords, so their swords got to the level of "able to cut barely protected flesh really well" and stopped there.
A one handed European "arming sword", by comparison, is
also able to lop off limbs with ease, and its more robust blade geometry and straight edge provides superior piercing and percussive-cutting (aka "chopping") capabilities, meaning it can compromise chain and plate armors, respectively. Plus, being one handed, it allows you to use one of those aforementioned shields, allowing for a greater level of defense.
*Deep Breath*Sorry, I've just had to deal with way too many weaboos who talk about the katana like western culture didn't spend a couple dozen centuries developing its own highly sophisticated ways of separating people from their lives, starting before Rome was more than a collection of huts.
But anway, back on topic, I suggest you go with either a Combat Axe or Mono-Whip instead of a katana. One or the other is the best bang for your buck, depending on if your effective Strength.