So basically the stats aren't so much "more X stat = noticeable increase in X" as it is "more X stat = better use of X," correct?

That said, this really is about luck, huh? A goblin with 5 attack can hit anywhere between 5 HP (die rolled 1) and 30 HP (die rolled 6), the difference between a flesh wound and your arm missing~

How would dual-wielding work?
Say if Jane had a rusty iron sword and sharpened iron axe and, for simplicity's sake, the sword conveys a +1 attack bonus and the axe a +2.
Jane attacks some poor goblin. 
Would her bonuses be combined to a +3, or would she make two separate attacks with their own respective bonuses (though that's essentially doing double damage every time you attack, so most likely not)? Perhaps it's a single attack that only uses the highest bonus, though that would make dual-wielding shit a less practical but still really cool and totally viable style.

[s]I'm also assuming that other factors can influence combat, like sneak attacks, magical debilitations and boons, poison, wielding a shield, and so on. 
...Though, I'm pretty confident that the answer to that will go along the lines of "we'll deal with it when we get there," aha! Not that that's a bad answer, of course.[/s]
Edit: This has already been answered, but I'll leave it up here as some food for thought.