So I know it's kind of a gag to hate Relm, but apparently based on observation it seems like it's also a gag to say she might "break your game", and I was curious what this was about. Is there really a glitch involving her that messes up the game?

On the SNES version or GBA? :O

Has to do with Sketch, iirc. I don't remember the details off hand.

The bug only occurs in ROMs and the very first SNES cartridge version (1.0; 1.1 would not have it anymore).

The bug happens when Relm misses the target she is supposed to sketch or when there's a difficult to sketch enemy. The bug has various possible outcomes, among them are dropping multiple items into the inventory (Gem Boxes, for instance), freezing the game or deleting all data.

It's the easiest to do on enemies who casted Vanish on themselves.

Dang, I never knew about that! And I first played the game on a ROM :O Never had the privilege of playing it in its original SNES form.. but that would've sucked royally to run into that little problem!

I remember coming across that particular glitch by mistake and suddenly having some of the best gear in the game. Or was that using the wrong Game Genie with my cart...?

Either way, the original FFVI was chock full of fun glitches. My usernick comes from my favorite bug in FFVI.

i didnt have a problem with her but i never use her anyway lol

I believe it was drawing on a vanished enemy or drawing while vanished... I want to say this worked best on the Brontosaur looking enemy while or after he had cast a spell that spun you around.....

This glitch rocked!! I would do my best to draw near a save point and find my way back. If you did this successfully you could restart your game (from your save point) with +99 of some of the best items in the game.