The devil is in the details.... Try firing Vestian and Ace of spades and listen to the sound....

This is true, but I feel like our guardian delivered the shot purely off the sound of the gunshot when the screen went black it sounds way more like Ace of Spades. Now it didn't sound exactly like Ace, but the Ace was also damaged at the time. This would be a good topic to debate though

In the cutscene the shot that’s fired also sounds like the vestian, not the ace

its was the Butler, in the Dining Room with the candle stick.

1. Listen carefully, both guns can be heard in the cutscene. 2. Riven calls us 'brother slayer'. 3. Our guardian points ace back at uldren and nods their head, as if they'd made the decision to kill him.

That is open for interpretion. And they did include Petra and the sudden black screen for a reason. Several points why Bungie did this: 1.) Some people liked Cayde-6, some not. Especially in D2 Cayde became more of a clown which I disliked a lot. So why should some people feel so connected to him? There was no real "revenge" feeling during my playtrough cauz I could give a damn for a clown like him. 2.) Uldren was used and his sister never tried to contact him. "Beytrayed" bis his sister, used by Riven (and Savathun) and left alone looking fot answers. If anything we should feel sorry for Uldren and a lot of people actually do. Was killing him justified? I think not. He was under complete control by an Ahamkara(!). 3.) Our guardian has no personality whatsoever. So it is hard to even think about what's your guardians opiniom about Cayde or Uldren. So, who shot him? Petra or your guardian? That is up to you. If you feel sorry for him the scene could be seen as Petra being the one who pulled the trigger. If you think revenge was the right thing to do, then yes, you can make yourself think your guardian was the one.

I actually have my own version of how it went down. My guardian ate Uldren.

I counted the bullets Uldren shot out of the Ace of Spades. Ace of Spades holds 13 rounds per cylinder. 1 bullet for Cayde-6. 12 bullets for the Shard of the Traveler. The gun was empty by the time we picked it up to aim at him. Then of course, you hear the Vestian Dynasty signature firing sound as the screen goes black.

obama killed ulden, change my mind.

You do make sense. If you listen closely when the screen fades to black, the gunshot sounded a lot like the Vestian Dynasty firing. Compare this to Uldren killing Cayde and the same situation happens... Ace of Spades gunshot noise. That is what I call 'attention to detail'

Both AoS and Vestian are fired, this is the beginning of the guardians journey into the darkness.

I just completed the story on my hunter and I heard a shot from the dynasty not the ace of spades, tbh I am actually mad because of this

There is also the sound of the shot that kills him when the screen goes black. Unless the Ace of Spades was converted into an energy weapon over the course of the story, it was the Vestian Dynasty that killed Uldren. Ergo, Petra killed Uldren

So we get all these dire consequences from Zavala for avenging Cayde's murder....and we get the Ace of Spades quest as a reward. Then we go out and avenge the Rift Cryptarch's murder and get get the Thunderlord for our efforts. If they really wanted us to be white hats, they would not be encouraging our homicidal tendencies.

Doesn't matter. Both our Guardian and Petra are responsible. Even if she pulled the trigger.....our Guardian was there and did nothing to stop it. This was a vendetta. Uldren murdered Cayde...and was not subject to City law....so we went out and got the only kind of justice that was left for him. Uldren knew what he was doing....and took pleasure in the deed. this is how people used to resolve such disputes before there ware laws and courts and prisons.