I may be wrong but Artur doesn't look like the player who is encumbered too much by loyalty. There's nothing wrong with that attitude, so show him enough shiny clinking stuff, and he'll readily put pen to paper. I don't think anything else will suffice.
Saints may have a tiny advantage in that a significant minority of the local population is Polish. But I reckon that would only count if the money was no better elsewhere. I could be wrong. In fact, I hope so because I personally prefer some loyalty to no loyalty, in a person.