The An Angel's Wish trophy in Borderlands 2 is story-related and can't be missed.
You will unlock the trophy once you complete the "Where Angels Fear to Tread" story mission.
*** Spoiler - click to reveal ***- Convince Claptrap to help
- Go to Thousand Cuts
- Meet Claptrap
- Deactivate barrier
- Destroy autocannons: 0/11
- Destroy bunker
- Open security door
- Destroy Eridium injectors: 0/3
- Steal Vault Key