http://www.handfasting.info/...actually, you might be able to encorporate it into a catholic ceremony, and none would be the wiser. One of my friends is catholic and part of the ceremony was similar to handfasting. After they put on the rings, a ribbon was placed over their wrists to verify the union. It wasn't perminant, but you might be able to talk to the clergy performing the ceremony into replacing the usual ribbon for something a bit more perminant (depending on how long you intend to wear it).
Hope it helps a little bit.
And Congrats
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