Q:
What is the skillful achievment?
It’s earned by unlocking skills. I’m not sure how many it takes to unlock all the tiers, but I can tell you that it takes multiple characters, and it seems only utility and elite skills count, not weapon skills.
It takes a lot of skillpoints to fully complete it. I’ve unlocked every skill on two professions, and quite a few more on others, and I still have quite a few to go.
This achievement really doesn’t get you anything but achievement points, so unless you’re desperate to beat somebody to a certain number, I don’t think it’s really worth it to try for this. Once you’ve unlocked the skills you want for a particular character, I’d recommend holding on to your skillpoints. You’ll need a lot of them to craft a legendary, so if that’s on your to-do list, then trying for Skillful would really be working against yourself.