Aquabreathers
Transmutationsplitter can probably still remove the rune.
1st person worldwide to reach 35,000 achievement points.
Data miners also found an item that would be able to remove a rune without destroying the item, but who knows if that will ever make it into the game.
My advice, for the limited amount of underwater combat that we do, don’t worry about it right now. You can add one later if you have the spare gold to dump in it. Or if you want to get the bonus now, throw the rune in there, and then just use a transmutation crystal if you need to move the rune to a better stat item.