I would highly recommend making the sword upgrades your first upgrade purchases.
There are two sword upgrades in the game that are required for this achievement to unlock. To upgrade your sword, you must speak to one of the inhabitants of Iripur (he is located approximately in the middle of town, next to the gray and red looking rock thing).
Please note that you can only carry 300 gold by default. In order to afford the second upgrade, you will have to first purchase an upgraded wallet. Also, you will need a total of 3 ore for this achievement.
Upgrade 1: 115 gold and 1 ore.
Upgrade 2: 350 gold and 2 ore.