Dragon's Dogma 2

The mystic spearhand vocation can be unlocked pretty early. After meeting Brant and finishing his first quest, take the oxcart from Venworth to Melve. Upon arriving, you will encounter a dragon attacking the town, and have to help defend with the townspeople. After taking off about a health bar and a half, the dragon will flee. At this point you'll want to locate the hooded man with the double edged spear named Sigurd, who should still be in the area of the dragon fight. If he is not in this location, travel to Harve Village, and finish the Scaly Invaders quest. Go to the eastern side of town, and the last house overlooking the ocean (Coastal Hut on the map) will have Sigurd inside. Exhaust his dialogue at either of these locations and you'll unlock the vocation.
Return to Venworth and go to the vocation guild, and change your vocation to mystic spearhand. The achievement will pop once you've changed.