SIG Sauer P220: McClane uses this pistol on the first half of the movie to battle the cyber-terrorists. Then after McClane loses the first fight to Mai Linh, she takes the SIG Sauer pistol as her own. Just as she was about to kill Matt Farrell with it, McClane rams over her with the SUV, losing the pistol. It was never seen again after that.
Beretta Px4 Storm: It was used by Russo when he killed two guards at Woodlawn. Then after McClane severely injures Russo, he takes the Beretta Px4 pistol as his own. He uses to kill Robinson, Trey and one of Gabriel's men. Then Farrell later grabs it an uses it to kill Emerson to save McClane and Lucy.
Beretta 92SB: It was used by a security guard briefly during the helicopter ambush scene. Noted by its rounded trigger guard.
Beretta 92G Elite 1A: Used briefly by Trey to hold on Lucy McClane.
Jericho 941: It was Gabriel's pistol. He shoots Farrell's leg and holds Lucy with it. Then he takes McClane with it to force him up and make him watch. Then when Gabriel uswisely uses the pistol to grind McClane's wounded shoulder, McClane uses this oppotunity to grab Gabriel's pistol and forces him to fire the round, going through McClane's shoulder and into Gabriel's chest, killing him.
Glock 22: FBI Deputy Director Miguel Bowman, as well as his agents and some Washington D.C. police officers carry Third Generation Glock 22 pistols. It was also carried by one of Mai's men on the Eastern Power Hub station. Then McClane uses it to briefly to kill one of the men on that station.