are the dual axes you get from the boss in the level under the place (vagueness to avoid being spoily) worth it?
It depends on
SPOILER ALERT. Click here to see text.
how useful liquid darkness is, as my guess is that they are coated with liquid darkness in a matter similar to daggers of venom, but it is just a guess.
Not to mention the mundane issue of weapon proficiency - axes are rather boring in terms of magical effects and artifacts, compared to many other things, so it's unlikely you'll be skilled in axes by the time you get them.