Well the only thing that really draws my attention is we do hear the gun being fired… after the bar man says "no blasters’
And we do not see it so I just came to that conclusion that the laser was missing in my head.
Due to the quick intercutting of the shots Ronster, the SOUND of the blaster doesn’t change the way I normally like to view this scene whatsoever.
In very quick succession, we first hear the lightsaber activate…quickly followed by the bartender yelling “No blasters, no blasters!” at the very same time as we briefly see Dr. Evazan’s gun raised in close-up…quickly followed by the blaster sound at the very same time we see Obi-wan swiping Dr. Evazan’s arm…lastly followed by the sound of the 2nd swipe towards Ponda Baba…
Therefore I just choose to explain the ‘missing’ laserbolt away like this - we don’t see it in the momentary, close-up shot of the raised blaster…because we DON’T see the front barrel of it in the shot anyway - the very front of the blaster is slightly offscreen when that shot is ‘paused’…
…and on top of this, it ISN’T yet heard to fire during that shot either. And then when we DO hear it fire in the following shot where Obi-wan has swiped at Dr. Evezan, the blaster happens to be unseen and offscreen now…
So I just like to believe that the blaster’s unseen laserbolt ended up missing Obi-wan somewhere offscreen…due to Dr. Evazan’s arm being struck and dismembered at this particular instant, causing the angle of his blaster to be suddenly off-kilter due to that.
Anyway, here’s the existing clip for reference - https://www.youtube.com/watch?v=Lfy5Esue_ls