Eiro twisted his hand counter-clockwise, pointing it at the small wooden cube in front of him. He was twisting the magic inside of it as per one of Partax's techniques, so that he could adjust some of its properties. Specifically, right now he was adjusting the wood's natural fire resistance, strengthening it in exchange for its general physical strength.
The reason he was doing this was quite simple; it was so that Eiro could gather experience simply doing different things, and interacting with different properties.