It’s difficult to figure out how Cassian got a blaster burn in the first place in Andor. Within the opening scenes of Episode 7 of the second season, Cassian is seen nursing a shoulder injury that has apparently been bothering him for a while. The episode doesn’t explain what happened to him, apart from revealing that it’s a blaster burn, leaving it up to the audience to work out how he got injured. (Warning: Minor spoilers ahead!)
Where did Cassian’s right shoulder injury come from?
It is suggested that Cassian got his right shoulder injury due to a blaster pistol while he was in the Rebel Alliance, most likely during a mission for the resistance.
The episode begins with Cassian, at his home near the Yevin rebel base, wincing as he attempts to rotate his right arm. Bix tells him not to say that it’s doing better and asks him to take off his shirt so she can apply an ointment. This reveals a rather deep scar that goes from his right shoulder to the middle of his back, suggesting that he was shot from behind.
Bix later reveals during a nighttime scene with an unnamed force healer, an old woman who is also a cook for the rebels, that the injury comes from a blaster burn, which is typically left over from being hit by a laser blaster shot. It also is not healing despite the ointment she applied earlier in the day.
While it might have assumed that Cassian got the injury during one of Luthen’s missions, the episode heavily implies that this isn’t the case. Cassian and Luthen have not been on speaking terms for roughly a year, with Luthen having to send Wilmon to communicate with him. Cassian believes that building an actual army is the more practical approach than merely solo missions from Luthen, with him telling Wilmon that “going it alone doesn’t cut it anymore.”
In a later scene where Val speaks with Bix, she says Cassian was on the verge of being promoted by General Dadonna and General Draven in the resistance before accepting the solo mission by Luthen. Val calls Cassian “a leader now” and says that they are no longer Luthen’s puppets. As Val lost Cinta during one of Luthen’s missions, Cassian also lost Brasso, so they would share a tragedy in losing a loved one.
Then in Episode 9, Cassian and Luthen have a conversation where the spymaster effectively wonders how the Kenari has seemingly appeared whenever he needs him the most. He recaps the missions Cassian has done for him thus far over the last two seasons of Andor up to that point, saying “Aldhani. Narkina. Ferrix. Sienar. Mina-Rau. Ghorman.” The gap between Mina-Rau, the planet where Brasso was killed, and Ghorman is telling, suggesting that Cassian hasn’t done much for him since trying to hide in Mina-Rau.
All of this points to Cassian having done some missions for the Rebel Alliance and getting injured on one of them. That said, it’s not out of the realm of possibility that he got nicked during, say, some training exercises with the new rebel recruits, but that’s not terribly likely. The fact that the wound wasn’t healing like normal could be one of the ways The Force was guiding him to the force healer, as he would not have been led by Bix to her if the injury wasn’t as serious as it was.
At any rate, he is seen recovering from the injury after the healer touched his shoulder, and by the time he accepts Luthen’s mission and leaves for Ghorman so that he can potentially assassinate Dedra Meero, he can effectively carry crates onto the ship using his right shoulder. Knowing how cautious Cassian is, he wouldn’t have gone on the mission if his shooting arm had remained injured.
