Unlike the other two Talismans that were sealed within the Pure Hearts of Sailor Uranus and Sailor Neptune, the orb was a mystical item which Sailor Pluto wielded on top of the immensely strong and powerful Garnet Rod she wields. Sailor Pluto was able to use the power of the Orb to pull the other Talismans from their respective Pure Hearts, which meant Sailor Uranus and Neptune were able to remain alive once they were removed. Apart from being a part of the Garnet Rod, the Garnet Orb didn't serve another purpose other than to summon the Holy Grail.