Eiyuden Chronicle: Rising

This is for maximizing the level for CJ's weapon AND armor.

You don't have to buy the five upgrades that will get your weapon (or armor) to (star) level 5. You only have to buy the upgrades from the Blacksmith in Outlander Lane! There are in total 30 levels for each weapon and armor thus it is required to grind for tons of material.
Make sure to use the right accessoires to have the best drop chance for the materials you need. You also have to buy level 3 upgrades for your axe and pickaxe from the Tool Shop at Second Street to be able to acquire the rarest materials.

For High-Purity-Ore I started at the first screen of the Quarry and made my way down towards the first checkpoint.
For Hardwood Lumber I started at the first screen of the Great Forest and went to the first checkpoint (which is located in the cave). On the way you will find plenty of rocks to get Durable Stone. You can either continue to the checkpoint just before the first boss to get more lumber or restart from the beginning.

Remember that you can also trade materials at Hogan's Shop at the end of Second Street!

Many of the final upgrade levels require you to have materials that are only found in the end game or dropped by bosses, so you will likely have to finish the game once, so that all the bosses will respawn.

I suggest to create a save game before going for these achievements. Concentrate on one character and when you got one of the achievements, load you previous save to regain all of the materials used. This will reduce the grind considerably.