Tales of Vesperia

Since there's no guide, I'd like to mention that this achievement is for synthesizing your very first non-story related item. More importantly, it has to be only and EXACTLY your first synthesized item, and it is very possible to miss this achievement if you decide to create multiple of the same item, (say, a few health items or something.) And if you do miss it, you can't get it with an EX new game, as your stats for total items made will carry over, so a regular new game is required. The same applies to the synthesize 20 items acheivement (which I seemed to get on the first go.)

So don't do what I apparently did and had to clean up this achievement almost 4 years after the last time I played lol.