You can just imagine evil spirits which exit from your card then good spirits which are enter in it.Another method is to light a candle and put on the cards then say "I bless this card.Blessed be,blessed be !".You can use a power of a deity to bless it,is good to say "With power of (deity name) I bless this cards".I don't heard about "pendulum on a tarot card" and sound a little weird.
Its uoto you how you choose tocleanse your deck even some peopledon't...
Oky some people usecandles andincense then they do meditation in which theyvisualise that a white light is falling upon them on the other hand some people just puttheir deck into moon light and under sun and sprinkle some tiny drops of water..
I smudge mine with sage smoke and I bury it in a container with coarse salt and leave it out on a full moon to charge it. When I first got my deck, I consecrated it by waving it above a candle, waving it above smoke, sprinkling it with salt water, and sprinkling dirt on it. You should search how to consecrate it/charge it. I still have to remember the steps and learn to do it correctly, haha. (: