Pop culture has a fetish for katanas. Apparently, they are just cooler than other swords and, perhaps, any other weapon as well. If it were just an aesthetic thing, it would be no big deal. But a mix of third hand accounts by Western authors, B-movies, anime and whatnot seems to have encouraged some very specific factoids about katanas that just do not stand up to serious scrutiny. Matt Easton addressed a fair number of these in a fortunate series of videos, which I heartily recommend. When it comes to RPGs, the following assumptions seem to be widespread: (a) katanas are the supreme cutting devices: they can cut through anything, including (obviously) any form of body armour, solid wood, steel, concrete; (b) in the hands of a proficient fighter, they are exceptionally agile weapons: they can be used to attack by drawing from the scabbard with few if any chances of defense, they can be used to parry all sorts of (melee and ranged) attacks; (c) they are virtually indestructible: only another (better forged) katana can break a katana blade. I will focus on whether katanas are depicted as inherently superior to all other swords, and on whether they are granted any exceptional feat unavailable to other weapons.
GURPS 3e did not include the katana in its core book. The weapon was, nevertheless, included in many supplements, most importantly Low Tech and Martial Arts. On the damage side, the game does not do anything dramatic: compared to its closest analogue, the thrusting bastard sword, the katana inflicts one more point of damage when used to cut and one point less when used to thrust. If one must think of this bastard sword as one of those acutely pointed longswords, it seems to make sense. But when it comes to other aspects, the fetish rears its ugly head. Low Tech, like the core book, states that a bastard sword can only by used one-handed with two severe penalties: it becomes unready after a swing attack and after a parry. Katanas have no such penalties, because, we are told, they are exquisitely well balanced. Martial Arts makes things worse by granting an entirely ad hoc defense bonus to skilled katana wielders: while in GURPS 3e the Parry value equals 1/2 of your weapon skill, a katana can parry at 2/3 of your skill, provided that you use it two-handed. It is hard to say whether this unfair advantage stems from katana fetishism or merely the will to assimilate katanas to fencing weapons (other privileged weapons in rules-as-written). Hilariously, this bonus was inherited by GURPS World War II: so players, do not even think of attacking a Japanese officer in close combat! Luckily, GURPS 4e openly reformed its ways and took katanas and (one hand and a half) longsword on the same level.
For a meaningful comparison in oWoD, you must peek into the old, nearly forgotten Combat supplement. Published at a time when (Asian) martial arts had become fashionable in RPGs, the book seems to mimic GURPS or HERO in giving martial artists cool maneuvers in order to make them better than anybody else in combat or, at least, more interesting to play. I will disregard this, and focus on the weapon stats. In this system weapons are differentiated by a number of parameters, namely Initiative, Accuracy and Damage. We are told that a bastard sword has a +4 Damage modifier, and and +0 otherwise. A katana, on the other hand, has +1 Initiative, +1 Accuracy and +3 Damage. Again, katanas are so exquisitively balanced that etc.
But those were the Nineties. Let us jump back to the present day. Savage Worlds, as we all know, is fun, fast and furious. So why care about verisimilitude? That would be slow, boring and, you know, non-furious. So the author decided to give katanas (a) a higher average damage than any other sword and (b) an Armour Piercing value of 2 against all kinds of armour, something that no other melee weapon has in the rules-as-written. I have not extensively playtested the rules, but it seems reasonable to expect that katanas are going to wound armoured opponents that other swords or pole weapons would not affect. This makes the katana by far the most attractive melee weapon in the game. Interestingly, this was so over the top that at least two licensed Savage Worlds settings discarded the Armour Piercing feat: not only the pseudo-historical Solomon Kane did it so, but even the chambara inspired Iron Dynasty did the same. It seems that katanas cutting through steel like butter are not to everybody’s liking, these days.