So, quick bit of context, I'm writing a story about a bunch of people trying to adapt to and live in a world where people suddenly start getting superhuman powers, worldwide, on a weekly basis, and the absolute and unpredictable upending of life as we know it that results. One of the main characters is a police officer who now finds herself trying to restore order after the latest batch of powers flings the whole world into anarchy by making guns useless, causing technology to only work when everyone around wants it to, making incarceration impossible by giving everyone a limited and un-aimed method of teleportation, and giving everyone what basically amounts to wolverine claws, resulting in the police being forced onto equal (and outnumbered) footing with the recently- escaped inmates of a maximum security prison. With this in mind, one idea I had was that since her husband, another one of the main protagonists, is a HEMA nerd who also does blacksmithing, she winds up forced to take the sword he made for her as a good-luck-charm and actually fight with it. And when I tried to picture what kind of "for-good-luck" weapon this hopefully-lovable dork would make for his police officer wife, an image suddenly sprang to mind of a cavalry saber (or other single-bladed sword) with a jet black blade and a blue cutting edge (he calls it, yes, you guessed it, "The Thin Blue Line"). Now, while this would be cute as a good-luck-charm and show of support for what she does, and while I think it would look pretty damned cool, the real question is whether I would be throwing realism out of the window by having such a colored weapon actually usable in a fight, and if I should have the "thin blue line" imagery present on the hilt or handle instead. Is there any method of coloring the metal of a weapon like I described that wouldn't damage its combat effectiveness? The coloring treatment doesn't have to stand up to extensive use (though that would be preferable), it just has to not result in an inferior weapon.