Tristan Delaney

Well yes he didn't give himself abnormally high powers, but he did use his acct to act well and above the power of other players. While these were not abilities gifted to him after they were still actions done. It could have been done by Asuna or anyone.

To be fair though he didn't just turn her into an item. He copied her program files (Her consciousness) And then created an item from that. The fact that a player copied a system file alone is really quite spectacular in the game universe. But then to take raw system data, and then create a brand new item, never before seen, and never to be recreated (Yui's heart is literally the only one of its kind) is another example.

Yui, as an AI never actually had a game acct. She was a system program who had system access. Everything she did was well within her spectrum of power, she had just been banned from doing so up until that point.

But If we are going to say no to this id say then Asuna when she broke Heathcliffs system granted paralysis of the players in the floor 75 boss room. Even he had said that he had not designed a way for any player to break paralysis on their own. To that effect Asuna became much more powerful than the average player. and had attained that on her own with no outside assistance of any kind.

(Srry, was typing while stopped at stop lights)

The only part of your argument I have issue with is the idea that Kirito used his account. The GM console was activated with Yui's GM privilege, the console just hadn't shut down by the time he used it. It's like saying you own a house just because someone left the key in the door. He didn't log in as Kirito or use anything that would assign him GM privilege. 

Pffft we all know the answer is really... Zero!