Sate: Wood Element Quest

Looking for clues because googling does not help.

I've finished the Holy & Unholy Swords up until year 315's clearing the mobs inside the mine and reporting back to D.Swordend. I then noticed that Sate has another quest (red exclamation mark). Being a quest junker that I am, I got that quest and all it says is...

"What is wood element? What powers does it have that it can silence notorious weapons?"

So I looked around and noticed that Granny Sephia actually knows something about the wood element and mentions Sandalphone and Manuel... before getting cut off by the textbox.

Clues, pointers, or how to fix this darn bug would be very appreciated