Hamish, that's some awesome advice about being aware of getting to that 'hard damage move' trigger position. Should be in the GM's guide for sure.
Glitch, so true! I was thinking that defy danger was an obvious alternative too. Perhaps the thief needed to just pin down what they were doing first. Its all to easy to shape the fiction to the 'fight' moves of Hack and slash, when really, we should always be saying what we are doing and then seeing if it triggers a move. Melee isn't always about Hack and slash and dealing damage.
In terms of monsters static damage and player rolled damage, maybe we can still make it seem fairer (especially if the fighter has just rolled a couple of ones or twos in a row), whilst still abiding by the rules, by offering them an opportunity with or without a cost?
'Hey you hit? Awesome, instead of rolling for damage, how bout you give me a wickedly detailed description of you dealing damage? If you do, you can deal half the possible maximum damage you could achieve (instead of rolling).' I'm a fan of the characters, yes?