Tree Slicer

Ever since written language became a thing, the medium in which have been written on has changed a lot. Firstly, large flat rocks were the main medium to use as they knew in ancient times how to make stone slabs and tablets. These tablets survived for many years, and many specimens have been found and are now on the local museums.
In today's Aewyn, a strong type of paper is mainly used for writings, as they have figured out a way to waterproof the material, and eliminate the risk of losing your work to the pesky rain.
But methods of making paper have been through a lot of development, and it hasn't been a great material to write on from the very start. The first known predecessor for modern-day paper, and the very first thing that vaguely resembles paper, is Tree Slices.
Tree slabs had also been used as writing tablets before this and were meant to be more portable than stone slabs - which there indeed were, but they were still too clunky to have on you.
Someone came up with the idea of trying to make the slabs thinner, which isn't a new idea in itself, and had been tried several times before, but it wasn't as much the idea of thinner wood slabs but rather the idea for a tool to make them with: The Tree Slicer!

The invention with the inventive name

So the name reveals the purpose and function of the tool, so it shouldn't be a surprise to anyone that it slices up the tree in some kind of way. Tree Slicers were made from sharpened metal - it could be bronze, iron or some other kind of metal, as long as it was sharp.
With an oblong metal blade, and two wood handles at either side, you'd sit with a tree trunk already cut in have between your legs, and then carefully cut a slice of the tree with the Tree slicer by cutting towards yourself, carefully!
There have been found logs of people getting hurt in the process of making paper for themselves. If you are just a tiny bit inattentive the blade might jut right though a leg of some other bodypart you'd rather not be cut (Which probably is any bodyparts)

Details

Year of invention

Around 500 years before Blue Lily Nebula appeared on the sky. But it wasn't a preferred medium in the first 1000 years of it being a known technique. 
It first became more widely spread when treatment for the tree slabs was invented as well, which made the surface better for writing on and made it last longer.

What impact did it have?

At first, it has close to no impact at all, as most found the new idea to be rather unuseful. The thin tree slices were easily torn apart, and the surface was rough and hard to make precise drawings and writings on.
In later years, when the technique got perfected a significant amount the tree slices got its breakthrough in society.
It was used a lot for nearly 2000 years before new ways of using tree trunks were invented, and the use of three slices died out from there.