Onyx Tears not stackable making them useless.

Is anyone else pissed off that you can't stack Onyx Tears. They're pretty much the best consumable in the game, now that you can't carry more than one of them at a time they are completely useless. I even tried to cheat the system by storing them in the retainer if they could be stacked there but it doesn't work. The max you can own per character is three.

For everyone who doesn't know what I'm talking about:

Onyx Tears is a potion sold by the Immortal Flames for roughly 3000 seals.
http://xivdb.com/?item/4563/Onyx-Tears

Onyx Tears would be the perfect item to buy with seals at level 50 and actually make seals useful currency.

What uh... what does it do? That link doesn't really explain anything.

You can't stack the engineering manuals either. Usually right before I start farming/crafting I'll buy one, use it, buy another, and then rush out to consume the buff before it wears off.