One of the biggest FAILS of the d20 era was the soulknife class, which debuted in the Third Edition era—although I can't remember now offhand if it was part of the original 2000 3e Psionics Handbook or if it didn't debut until the 3.5 Expanded Psionics Handbook in 2004. I admit to not being very well-versed in 2e, but I don't believe that there were any soulknives in 2e.
So, the soulknife can form weapons out of raw psionic ability, and supposedly fight kind of like ninjas or something. Again—not at all a bad concept, but just a terrible execution. The soulknife blade doesn't keep up with a normal character's weapons, the BAB was mediocre (extremely curious for a supposed melee class) and it was a bit on the mobile side, but less so than even the monk. It couldn't wear much in the way of armor, so it was beat up a lot, although it did have at least decent hit points. And it had no real psionic powers to speak of other than the blade itself.
Like many, I liked the concept, but wanted to "fix" it. My first efforts were pretty modest—just changing the BAB to full fighter-style BAB, and leaving everything else as is. I eventually, however, saw the class as pretty much the same archetype as the Jedi—except that instead of a lightsaber that was mechanical hilt with an energy blade, it had weapon of psionic energy that it could call and banish at will. Future efforts to "fix" the soulknife therefore actually started with various d20 Jedi classes rather than with the actual soulknife itself. Of course, to do this properly, I'd have to have had a para-psionic magic system, giving the soulknife psychic abilities like the Jedi powers, or else somehow adopt d20 psionic powers to the class somehow, which always seemed like more work than I was interested in.
When I migrated from d20 to m20, I initially gave no thought to any kind of psionics or anything like it at all—however, I did create a Jedi class for my m20 Star Wars conversion. When I eventually decided to raid my m20 Star Wars conversion for my m20 fantasy games, making the Jedi into some kind of soulknife analog seemed not only easy, but potentially kind of cool. Thus was born the Shadow Sword, where I take the Jedi mechanics, get rid of the Force Powers and instead give it some mystic ninja-like powers, etc. and off we go. I've got the soulknife I want, finally—converted from a totally different base into a totally different system.
As Pulp Revolution as a movement continues to get off the ground, I'm even more inclined rather than less—and I'll admit that at various times in my life, my tastes have been all over the map on this question—to look for nominally science fiction conventions to loot into my fantasy, or vice versa. So, in AD ASTRA I expect sword fighting on space ships (and to be fair, it's not like this isn't pretty common already. If Star Wars wasn't enough, Guardians of the Galaxy certainly added even more of it to the canon of mainstream space opera.) And in FANTASY HACK and even DARK•HERITAGE itself, I've got Psylocke/Jedi.