Why did Obi-Wan lop off Ponda Baba's arm?

Question

In the canonical novel Journey to Star Wars: The Force Awakens: The Weapon of a Jedi - A Luke Skywalker Adventure, Luke recalls the incident in the Mos Eisley Cantina as follows [emphasis mine]:

Luke’s mind flashed back to the Mos Eisley cantina, where two alien thugs had picked a fight with him. Ben had tried to play peacemaker, sensing Luke’s growing panic, but the aliens hadn’t been interested in peace. One had flung Luke into a table, then gone for his blaster, ready to gun Ben down.

The old Jedi’s hand had dipped to the lightsaber on his belt, faster than anyone would have imagined a desert hermit could move. His lightsaber sliced the blaster aimed at him in two, then carved through the thugs.

This makes it clear that Obi-Wan delivered two strokes, and that the first had cut the alien's blaster in half; only after this did Obi-Wan chop off his arm.

The question, then, is simple:

Obi-Wan had already disarmed Ponda Baba (no pun intended) - so why did he continue the attack and remove the poor guy's arm when he no longer posed a threat? Isn't this an unnecessary use of force (again, no pun intended)?

Answer 1

Watch the scene closely. In the footage, we see Evazan draw his blaser; Ponda Baba is obscured behind Evazan in that shot so we can't see if he's drawn his blaster. Obi-Wan swirls his saber and then makes a single sweeping motion that knocks back both attackers at once. The camera then pans down to Ponda Baba's arm, still holding his intact blaster.

We don't see exactly what Obi-Wan is hitting with the lightsaber, but it looks like the initial swirl was intended to disable Evazan's blaster, while the second swing disabled both attackers. Again, Ponda Baba's blaster is still intact on the floor, so the Aqualish was still holding an intact blaster when Obi-Wan cut off his arm.

Answer 2

The way I see it, Obi-Wan had already decided to remove his arm when he drew the lightsaber. The initial strike to disarm Ponda (of his weapon) is just to be safe. It would only take a fraction of a second to pull the trigger, it could even happen unintentionally when being hit somewhere else. By destroying the weapon you minimize the risk of being hurt.

It has also been done before, Mace Windu chops of Jango Fett's hand before removing his head in Attack of the Clones.

The reasons for Obi-Wan's decision to cause serious damage is in my opinion explained by Eike. He was outnumbered and wanted to end the conflict quickly. Also, the "poor guy" is a wanted thug, Obi-Wan did the world a favor, if you ask me.

Answer 3

In a society with really good bionic limbs (such as AGFFY), cutting off a hand or arm was generally considered a humane way to win a fight. Lopping off the head was considered (wait for it...) overkill in most cases and "not the Jedi way."

Answer 4

The intention on Obi-Wan's part seems to be to end the fight as quickly as possible, in a way that results in the minimum chance of a second attack but without necessarily killing the guy. Merely chopping his gun in half would still leave him free to attack with his hands.

Disabling him was an immediate and highly effective way of ending the fight in just a few seconds. On top of that, it meant that he wasn't obliged to use the Force in the fight, something that would have immediately blown his cover:

Luke looked up from where he was sprawled on the floor and saw Ben’s hand dart to his belt and draw a lightsaber. The blade flashed on and swept past the blaster-wielding criminals. The disfigured man fell back against the bar, a deep slash across his chest. The tusked alien screamed and his right arm — severed at the elbow — fell to the floor, still clutching the alien’s blaster.

The entire fight had lasted only a matter of seconds. Luke hadn’t noticed just when the band had stopped playing, but he was suddenly aware that everyone had gone silent, and the only sound in the cantina was the hum of Ben’s lightsaber. Ben maintained his position, holding his lightsaber out from his body as he stared at his two defeated opponents. He glanced out across the room. If anyone else had been looking for a fight, the look in Ben’s eyes was enough to discourage them. - _{^{Star Wars: A New Hope - Junior Novelisation}}

Answer 5

1. If the blaster is removed from the situation, and you have a laser sword, and the other guy doesn't what further incentive do you need to prevent retaliation? You are armed, and they are not. Them attacking you in hand-to-hand; is basically suicide by jedi at that point. He could have simply put gotten their blasters, and the fight would have been over.
2. It's a lightsaber in a bar. His cover is blown, as only jedi use lightsabers.
3. We see that this is the kind of bar where people mind their own business. When Han shoots greedo later on; no-one intervenes, or tries to stop him when he leaves. Our conclusion should be that while two violent encounters in a day might be uncommon at the cantina, armed, violent conflict is common enough where everyone knows to stay out of everyone else's business. As such, there was no real reason for Obi-Wan to act as if he needed to intimidate everyone in the bar by brutalizing one of the perps. Neutralizing the perps, would have been enough. But no. He went back for seconds and took an arm, just because he felt like it.