I just punched it up on FFXIAH, and it's showing one for sale right now... hasn't sold on the AH in a month.
Have you thought about doing the ENM? Or not worth the effort? :\
Isn't something that can be soloed unfortunately; you need at least 3 people to even access the battlefield, and it's not going to be a total curbstomp either because "uncapped" ENMs are still level capped at 75, so you can't go in expecting to be 99 and stomp it.
And even if you can beat it, the drop rate isn't great and you can only try once per 5 days.
May I ask what you're wanting/needing the Martial Knife for?
Aeolian Edge spamming is about the only thing it's good for, so probably that?