Basically this happened (Wikipedia copy/paste, too lazy to type it out myself):
In X-Force (vol. 3) #4, Warren is brutally attacked by a mind-controlled Wolfsbane. During the attack, Wolfsbane savagely rips Warren's wings from his back and runs away, taking the wings with her.[42] It is revealed by Elixir that Warren's wings are still techno-organic constructs that he is unable to heal.Wolfsbane later delivers them to the Purifiers, who are seeking the Apocalypse Strain, the techno-organics, which comprise Warren's wings. The Purifiers use the Apocalypse Strain to modify an army of Purifier agents, giving them the same metallic wings that Archangel once had. Meanwhile, although Elixir is able to heal all of Warren's injuries, he cannot regrow his wings due to interference from the Apocalypse Strain. Later in the story, Warren is gripped by a series of excruciating seizures that not only mysteriously regenerate his techno-organic wings, but also transform him back into Apocalypse's version of Death/Archangel, complete with blue skin and a techno-organic version of his uniform.[43]
X-Force attacks Archangel, who eventually asks for relief from the pain of losing his wings and transforming into Archangel.[44] However, at the last minute, Archangel escapes into the night, intent on taking vengeance against the Purifiers. Warren arrives at the Purifiers' headquarters and slaughters most of them in a blood-maddened rage. However, once the battle is over, he reverts back to his normal Caucasian, feather-winged appearance. He comments to Logan that he can still feel the metal wings inside him, however, and that they want to come out again. According to Elixir, Warren's transformation is permanent, implying that he is fully capable of transforming back into Archangel again at any time.[45]
In an attempt to understand what was done to both Wolfsbane and Angel, the pair of them are placed in a room together, where Rahne is forced to gaze at Warren. The mere sight of him causes her to become murderous once again, and she attempts to rip the wings from Warren's body once more. The sight of a psychotic Wolfsbane, as well as the fear of having his wings torn from his body again, causes a defensive reaction in Warren, reverting him back into his violent Archangel persona.
From then on, Angel takes dual membership with both the X-Men and X-Force, though Cyclops forbids Angel from telling the rest of the team about the return of his Archangel powers.[volume & issue needed] However, while recruiting a scientist for Beast's "Science Squad", the X-Club, Angel is forced to transform into Archangel in order to destroy a giant rampaging monster. Beast reacts in anger that Angel has not told him that his "Death" powers have returned, creating tension between the two friends. Angel knows telling Beast would expose the latest incarnation of X-Force and effectively end Cyclops' latest tenure as leader if the truth about his personal black ops squad became public knowledge.[volume & issue needed]
During the X-Club's trip to 1906 in order to discover the origins of the modern mutant race, Angel transforms into Archangel a number of times to help further their mission.
During the Fear Itself storyline, Wolverine and Archangel interrogate Purifiers member Benedict Ryan on where Jonathan Standish is hiding out.
