I think this is interesting, and that the direction you're going in is a better fit for WW than the standard DW hack & slash. Since you've got humours rather than hp, DW's hp-centric approach (particularly the "take damage yourself to do +1d6" option) isn't going to work well, and I like the idea, in the draft I saw, of the PCs not being by default very combat-capable.
However, it seems to me this needs some work. Mostly, the trouble is that you are hanging the mechanics onto fictional elements that seem subjective and muddily defined. What is "seriously badass"? What is "skilled or disciplined"? What happens to a variety of foes, of varying degrees of skill and discipline, on a 7-9? Is it really irrelevant to the mechanics if you're facing one foe or twenty? There's also a great deal left to the GM's discretion. This is fine, of course; the hard choice on the 7-9 and the hard move on the 6- are always ultimately the GM's call. But part of what specialized moves bring to the table is a quantification of costs, so that players quickly and intuitively know what they're risking when they roll. This can aid drama; the stakes being known only to the GM can feel arbitrary.
In AW, combat move downsides are usually some flavor of "harm as established", meaning you know going in what weapons, and thus what damage, you're going up against. In DW, the focus is on your enemies "attack" -- it lands on below 9, and lands if you go for the extra die on a 10 up, and thus how well you understand the stakes has to do with what the enemies attack is. This allows great flexibility, too, with different monsters being different, but also some clarity: a giant tentacle might just bind you, or do squeezing damage. The GM has time and a specific prompt, to reflect, when drawing up the monster, on what it's attacks are and what they do. Here, the issue seems a bit muddied: "an imbalanced humour or other resource". Also, what if you're humours are already imbalanced? Do you get to imbalance a different one? Or is it a feature of the monster, like something with a heat attack is going to imbalance one humor, something that cuts and bleeds you will imbalance another? Seems like a place there could be some crunchiness to the mechanics, giving both player and MC some clarity.
Similarly, as a GM I could use a little guidance in distinguishing between "serious consequences" and "something minor" -- it seems like I need here as crisp a distinction as hard vs soft moves, or "success at a cost" (7-9) and "failure" (6-). These are intuitively understood, so we know what's at stake when the dice roll. I need a succinct intuitive way of understanding what advantage "advantage" concretely confers.
For clarity, I might split it into three moves: "when you enter melee", "when you have the advantage and press the attack", and "when your enemy has the advantage, and you fight on".
What happens if you enter melée, but then decide to withdraw and not press the attack? Is there a move for that, or is it just defy danger?
What happens if you get a 7-9 on press with advantage and decide not to finish them off (because you don't want to pay the minor cost)? Does the battle go on? Do you retain advantage? Have you dealt any damage at all?
On a 7-9 on press without advantage, if you don't want the consequences, who decides whether you retreat or yield? Is it "retreat if possible, but the GM may tell you that you'll have to yield instead"? In which case, when does the GM have to tell you this? Before you begin combat in the first place, when you lose the advantage, or when? What about an enemy that wants to kill you -- in which case "yield" is a non-choice? Then a 7-9 just feels like a failure -- "you take serious consequences, or else accept being killed" -- which doesn't feel like a 7-9.
"You can either yield or attempt to withdraw" seems to invade the PCs' agency a bit too much. What if my character would NEVER yield or withdraw? What if he's bloody Conan, or he's declared he's going to fight to the death? Perhaps the advantage is simply no use to me then, and I am down or captured. Or does combat just continue, with me having taken some kind of damage? That's not in the text.
If I'm unwilling to yield/retreat, having advantage actually makes no difference when pressing except on a 7-9. On a 10+ it's irrelevant because I win regardless. On a 6- I lose regardless. On a 7-9 the only difference it makes is the cost of the price I pay to win.
Since there are various ways in which combat can continue past the first press (for instance, i don't pay the price to retreat), what happens on the subsequent round? Is it the same move? It seems odd that advantage stays static -- that there's no cost called "lose the advantage".
AW-hack combat (and other) moves usually scale so that you can decide if "one roll for the whole battle" or "blow-by-blow" is more dramatically appropriate. Here, it seems like you've tied it to a 2-move combat every time, whether I'm just trying to show my brother who's boss down by the creek, or fighting singlehandedly to escape from belowdecks of a pirate ship against its entire 30-pirate crew, or (does it work for gangs?) trying to take an entire castle with my siege engines and leigionnaires.