The repeatable quests in the Valkyrie area of Calpheon appear to grant these as a reward. Once you gather 7 of them, you can place them together in your inventory (the tooltip shows how); this will allow you to combine them. The combined item will grant a quest to open the Valkyrie treasure chest in the tower (my reward was crap - 10 medium hp potions). You can then look the chest as well as turn in that quest.

This pattern works on EU-Servers

10 Medium potions for me as well. The current iteration of the quest requires you to arrange the 7 swords into the shape of an "F". The vertical is five swords-high and then a sword each for the crossbars:
**
*
**
*
*

Combines to: Valkyrie Dagger

The current version for TAIWAN server seems to uses a different pattern than what I have seen on various websites/comments.
Found the correct pattern after many tries... as follow:
X O X
X O X
O O O
X O X
X O X
Remember to right click the combined dagger to accept the quest first, otherwise no option to open chest will appear.
Reward seems to be the same as anyone else, stupid 10x potion.
Just jump down from the tower and suicide -.-

Man muss aufjedenfall mehrere Daylies mitnehmen