Maker - Alchemy Skill FAQ and Walkthrough

So, can the skill be used on Timeless Weapons?

Let's say you fully level a Timeless Weapon and want to get awesome stats on it. Can you use the Maker Skill with 3 High Grade Crystals to get another 9 Attack and THEN scroll it using scrolls?

No, maker skill literally MAKES things from materials. IE, you'd have to use Maker to create it before you could equip it and level it or scroll it.