The 1 Minute Butter Knife token allowed Lex to use the Butter Knife at its full strength for a duration of 1 minute. Perhaps if he had used it as a sword or dagger instead of throwing it, he would have had access to it for the full minute instead of a single attack.
Yet it did not matter, for the damage he did with that single attack was far greater than anything he could have achieved by simply swinging it around.
All those who had attacked the Inn, or were secretly planning on attacking the Inn had been gathered by him in one location - not so that he could attack them but so that they would not cause trouble.
This raised the question of how Lex knew who the people were who intended to cause trouble when even the system failed to detect their malicious intent. The truth was, he was not detecting malicious intent, but his eyes saw them connected by Karma. Of course, Lex had no idea what Karma was, or how it worked.