So i was doing some of the starter quests for the grand companies (the maelstrom specifically) and after receiving my first seals i found this little precious scroll at the seal exchange npc.
These items give increased sp on synthesis. (theres a gathering variant of the scroll available as well)

Now i havent seen any topic on here in regards to these so far, so i dunno how many people know about them.

So anyway i decided to try one out and it give me about 40-50% more sp on a 3hr duration, at the rank i tried it out on. I dunno if its really a % or based on rank, or fixed and based on rank or such.

Just figured id put the info out there since i noticed there wasnt anything on the item at yg.

It's quite awesome for skilling up.