This achievement was a bit glitched for me. I had to purchase the following:
* two peglegs
* two eye patches (one was the day 1 patch that cost 1 gold piece)
* one hat
* two hooks
The achievement unlocked for me after purchasing the second pegleg. I did not have to equip it to unlock the achievement.
I know achievements were glitchy the first few weeks after release, so YMMV.