Complex sentence: It was this confrontation with Sharpe that convinced Stark to also champion the Registration Act as Iron Man, however, Stark had in fact already been covertly supporting Registration Act even before the Stamford disaster.
Split into simpler sentences: It was this confrontation with Sharpe that convinced Stark to also champion the Registration Act as Iron Man. However, Stark had in fact already been covertly supporting Registration Act even before the Stamford disaster.