I think the exponential costs of forging is likely closer to the reality (might even be more harsh than you are suggesting). I don't believe a 0.5 ETH floor is likely for diamond axewoman (though I hope I'm wrong). The floor for Diamond legends in DO is hovering around 0.25 ETH at the moment and thats with a limited supply of these. Assuming forging opens up you could in theory have an unlimited supply of diamond axewomen ultimately the market will reach some sort of equilibrium I believe the markup will end up being slightly above the $GODS cost to forge it. Might can get to 0.5 ETH if it costs 1000 $GODS to forge however if costs are that high that will greatly limit the amount that can be forged. Also interested to see if they make flux relevant with higher shine forging. Either way its pretty much a shot in the dark right now.
RE: How Much for Diamond Axewoman?! (WARNING: MATH ENCLOSED!)