Today I learned: "I owned you at <x>" is a slavery metaphor. It was always just something I said. Now I know, and therefore probably can't say it anymore...
If no one in the context of the discussion finds it offensive, I would say it is fine to say it. If the original meaning of a word has become archaic, then I cannot see a rational reason why one cannot say it. If someone becomes offended by usage of the word, then maybe your position should be re-evaluated, but most insults have their history in bigotry, and trying to cleanse yourself that way is not productive. The word "git" comes from the word "beget", insinuating that they are a forgotten offspring: a bastard. Some people would be offended by being called a bastard, because of it's meaning of being born out of wedlock. But I cannot see anyone being offended by being called a git for it's original meaning. The term no longer means what it does, and censuring it as such does not make sense to me. The same might apply to "I owned you", though I don't know the term so well, so I can't really comment.
Though it is my example, I would add that I don't think that it started out as a slavery-of-others metaphor.
So, before there was "pwned" there was "ownership." You "owned at the game" rather than "owning the other players." The ownership was to entitle that your mastery of the game was so complete that you transcended mere "participation" in the game and instead cultivated "belonging."
Unfortunately, etymology is something of a footnote in real life.