Hmm...let's see if i can get a response out of this dead forum xD
So i got problems unlocking the love emblem and the achievement tied to it.
I finished the game 2 times and got all other achievements.
Each mission using 1 weapon only...still no achievement.
I used other weapons by accident a few times but reloaded the last checkpoint afterwards, do i have to restart the mission?
Any other help is appreciated.