I think the inclusion of reapers mark presents an opportunity to provide shorter Athenas voyages by adding some risk vs reward in the mix. My thinking is an Athena voyage with maybe riddles that take you through a few islands, with the final destination providing a chest. But the catch is, you have reapers mark active at all times.
This would provide far more risk in the sense that people would feel motivated to go after every Reapers Mark they see for that tasty Athena rep, prevent alliances from being formed while the voyage is in progress, spark up the PvP experience a bit, and provide a potentially shorter method of going after those legend chests. I mean, they are legends after all, so the potential for a battle shouldn't be any deterrent. The system could automatically disband current alliances to prevent people from server farming and everyone benefiting, and from what I understand you cannot put up an alliance pennant while flying the reapers mark.
I have also thought that maybe it's time to allow Athena voyages to be picked up off the table and resume later. It's clear that many issues can occur that can waste a lot of voyage time and cut it short, resulting in the loss of the voyage. I understand the existing limitations and why they are there, but I know personally one big deterrent from booting up every day is my crew simply doesn't have the time to invest during most weekdays. And without my crew, I'm really not likely to hop in. I get it might not make sense for other voyages, and there's no real incentive to finish non-legend voyages anyway, but for Athena I don't really see much harm in allowing it to be resumed at a later date. Perhaps it's too prone to exploiting, and I wouldn't want to combine this idea with my previous one, but it's a thought.