To make your system a bit fair, forget your zillion speech bubbles idea - by the time you see them, it could be too late for them to do any good.
What "zillion speech bubbles idea" are you referring to? I don't think anyone mentioned anything about speech bubbles.
Oh sorry, I misread your post. You had the impression that everyone in the entire world would naturally look at durability numbers and see the same imaginary gradient which "takes place in the player's imagination." That is wrong.
That was actually just an example of what someone might realistically say when trying to repair something (if Divinity and its mechanics were real-life). Mainly because someone said the cut-off points were unrealistic.
The point was that durability numbers are just a concept that are obviously supposed to mean something else to a player. If you had some passing knowledge of sword repair and looked over a slightly dinged sword, you could probably fix it. If, instead, it were heavily damaged, you may find yourself facing a problem beyond your skill.
The game represents concepts like those by showing you (using the above example) 55/60 and 20/60 durability. Yes, since we're not showing you a highly detailed 3D model of the sword to zoom in on and pan your camera across the blade as you inspect every chip, scarred, and dulled edge, you're expected to rely on your imagination a bit and understand that the numbers represent an idea the game can't represent to you visually.
So, yes, there is going to be a point where X = can repair and X-1 = can't. Because X, in that case, means "just barely able to" and X-1 means "just barely beyond my skill". Some people seem to be looking at it as X = "can do this with my eyes closed" and X-1 = "impossibly broken", and that's just incorrect. There is an implied gradient over the range of numbers, rather than it being all black and white.
