Mnemosyne's Forge is the 2nd Forge in Castaway 2. There you can craft Scholar's Sword (Scholar), that you need to combine Sorcerer's Sapphire and Regal Sword.
Mnemosyne's Forge, the 2nd Forge
The quest "Brains Over Brawn" would be related to this Forge, so it tells:
When you will follow this quest, there you can see is the required item, but you don't know what items you will combine to get the required item. So here you can tell:
Scholar's Sword - means it is a required item, so you need to have that item to complete the quest.
So you can not know what items should combine to get Scholar's Sword?
Do not be worry. Here are the items you need to combine:
The first one is Sorcerer's Sapphire. It located below the Forge of Nymphs.
The second one is Regal Sword. It can only be bought at Astraea's Bastion, in the weapon's section.
So if you combine 2 of them, you get Scholar's Sword! But the Scholar's Sword can only be crafted once, so you need to careful to not dispose this sword.
Notes about Mnemosyne's Forge[]
Mnemosyne's Forge is the 2nd Forge in Castaway 2, located above Astraea's Bastion, and blocked with a Village Gate. To get the key, kill Petunia the Angry first, so the quest "Anger Just Leads To More Violence" can be rewarded from Sigil a Village Gate Key to open Village Gate.