Seal of Metatron (Parted Souls)

The "Seal of Metatron" was used (It is one of two ways to be sent back to the real world, Vincent Cooper had the Halo of the Sun carved into his chest to be sent back.) to send Sharon Da Silva back to the Real World, this seemingly only sent the "Good" side of Alessa Gillespie back.

"To the town's religious organization, the Seal of Metatron is an ordinary talisman with no particular significance. As Alessa was unable to spread this crest throughout the entire town in the first game, its power was never demonstrated. In spite of this, both Vincent and Leonard misunderstood its abilities.
 * —Hiroyuki Owaku"

Backstory (Games)
While this theory isn't about the games, let's look at the game's seal then talk about the film's seal.

Silent Hill 1
Alessa Gillespie inscribed the symbol around the town to try and prevent the birth of the Order's "God". In an attempt to mislead Harry Mason during his quest for his daughter, Cheryl Mason, Dahlia Gillespie convinced him that the symbol was that of Samael (often times attributed as the Angel of Death). At the end of the game, Dahlia tells Cybil Bennett that if Alessa completed her quest in placing the seals, all would have been for naught.

Bound by the Order's spell and living in an endless nightmare in agony, Alessa's wish was for a complete death. Since she was unable to die in a normal fashion while under the influence of the power of the malevolent deity, Alessa intended to "annihilate" herself by the power of the Seal of Metatron with the nightmare world at hand.

At the moment Cheryl and Alessa united, she gained the power to escape from the Order's spell; at the same time, the technique that brought about the descent of the cult's god succeeded and the malevolent deity resumed its maturation process. This time, Alessa was engaged in a struggle, a race between the malevolent god's maturation and the seal's completion. If the seal were to be completed, Harry, Cybil, Dahlia and the others would all be annihilated along with Alessa. This is why Dahlia fools Harry.

Alessa was creating the Seal of Metatron at the school, hospital, antique shop, lighthouse, and amusement park. Drawn lines connecting these seals and their placement creates an enormous Mark of Samael throughout the town.

Silent Hill 3
Convinced by Vincent Smith that the Seal of Metatron would prevent the birth of the Order's God, Heather Mason hunted down Leonard Wolf. Considering himself appointed guardian of the symbol, Leonard proceeded to attack Heather. With his defeat, Heather was able to obtain the seal. In the end, however,Claudia Wolf proved it ineffective.

The attendant of God, Valtiel, has the Seal of Metatron tattooed on each shoulder. It is important to note here that both Metatron and Valtiel were described by Silent Hills scenario writer, Hiroyuki Owaku, as "agents of God" in the Book of Lost Memories.

Heather is given a book entitled "Otherworld Laws" by Vincent which reads:

"This magic square, with strong protective and dispelling properties, is called the 'Virun VII Crest' or the 'Seal of Metatron'. It will bring results regardless of whether the target is good or evil; its strength, therefore, places a very high burden on the caster. As it is also difficult to control, it is not usually used. This is why it bears the name 'Metatron', after the angel Metraton (or Metatron), also known as the 'Agent of God'".

"Metatron" and Hebrew Culture
Now, we use wikipedia for some more info on "Metatron", the main reason this article (And the seal itself) is here.

Metatron (in Hebrew מטטרון) is Enoch, ancestor of Noah, transformed into an Angel. There are no references to Metatron as an angel in the Jewish Tanakh or Christian scriptures (New Testament and Old Testament); however, in the Book of Genesis, 5:24 is often cited as evidence of Enoch's ascension into an angel - "Enoch walked with God; then he was no more, because God took him away."

Although he is mentioned in a few brief passages in the Talmud, Metatron appears primarily in medieval Jewish mystical texts and other post-scriptural esoteric and occult sources.

Now this is the best part.....

Judah Leib Rapport in Igrot Shir suggests that Metatron is a combination of two Greek words which mean to "change" and "pass away" referring to Chanoch (Enoch) who "changed" into an angel and "passed away" from the world.

Now this could be the reason that Sharon was split again, but i'll get back to that......

Event's of Revelation
This is still under work. Give me some time.