If you look at the original classes, Fighting Men and Magic-Users each have one general power and one scaled power:I've been thinking about ways to fix this, to get back to the two-class-abilities standard. One thing I feel is important is to ask "what is character class really about?" I've said before, I don't think it should be about professions: I would cover that with backgrounds. I prefer to think of character classes as answers to the question "how do you solve problems?"Fighting-Man: use any weapon, multiple attacks against 1HD creatures.[ ... ]
Magic-User: use magic (scrolls, wands, staves,) prepare and cast spells.
Clerics came later and kind of break that pattern [ ... ] Thieves break the pattern even more, partly by having a whole bunch of abilities that scale, partly by most of the abilities seeming trivial at 1st level compared to the other classes.
Fighter: "I solve problems by fighting."One of my problems with Clerics and Thieves is that they seem more like professions and don't seem to clearly answer that question. Leaving aside clerics for now, I think the thief archetype, stripped of the assumptions based on thievery as a profession, answers the question with "I solve problems by subtlety and guile." This covers more ground than simply "I steal stuff," and could describe scouts, for example.
Magic-User: "I solve problems by magic."
The problem of having many scaled abilities can be solved by bundling several of them together under the subtlety and guile focus: instead of having individual advancement in "thief skills", treat hiding in shadows, moving silently, picking pockets, and backstabbing as things just about anyone can try, but make their success dependent on surprise. The thief scaled power is now a +1 bonus per 3 levels (rounded up) in subtlety and guile situations. Phrasing it that way lets me use the bonus for avoiding surprise (hear noise, spot hidden) as well, or deciphering or creating a subtle trap, lock or trick. You could even stretch it to cover the subtleties of language or magic. Only climbing would get dropped as a special ability; the revamped thief class would climb as well as anyone else. Thieves' Cant would only apply to the thief background, not to the class.
I'd change the surprise mechanic to both sides rolling a d6, with the higher result surprising the other. Some creatures can't be surprised, and a creature that is unaware of the other's presence can't surprise, but both sides still roll a d6. Thieves add their bonus to the die roll; if their target can't be surprised or if they are unaware of their opponent, the bonus is only counted to resist surprise. If a thief makes a successful surprise attack, their total is counted as additional damage. When deciphering clues in languages they otherwise don't speak, figure that average languages have a +6 bonus to resist decipherment; magic is even harder, adding the spell level to the difficulty. Further, when casting spells from scrolls, I'd have the thief player roll 2 dice, risking a miscast on doubles.
Under this revamped system, anyone could try any of the thief abilities, but probably won't succeed on many of them without getting bonuses from some other source, like magic or special training. Thieves will still be the best.
There are still two problems. One is that the name "thief" certainly doesn't fit, and "rogue" doesn't necessarily fit, either; this is OK in and of itself, but I can't think of a better name for "the crafty and subtle class". The other problem is: what's the other class ability? What's the general, non-scaled subtlety-based class ability that only this class should be able to do?