Abstergo have the ability to manipulate time and space with the artefact, but dare not try in case of triggering paradoxical events. It's possible that Desmond will use such an artefact to stop Abstergo before they even begin their operation.
Email: "Tunguska Incident - Now believed to be the direct result of assault by Assassins. Research station destroyed as was artefact. Alternate wave generation devices have been located in storage, but we have insufficient data at the moment to initiate research. The risk of accident is too high.
Lineage Discovery and Acquisition Division should attempt to locate descendents of any attack survivors (either Assassin or Brotherhood) in order to continue research. Resurrecting this particular type of technology will aid us greatly with any holdouts following the Satellite's activation. We're putting together a team to push research in this area."
Explanation: On 30 June 1908 a massive explosion rocked the world. The incident, near the Podkamennaya Tunguska River in Tunguska (now Krasnoyarsk Krai of Russia) is believed to have occurred when a meteorite burst above the Earth's surface, flattening trees and causing widespread destruction. The email states that it was caused by a group of Assassins destroying a Templar base and the artefact at that location. Abstergo obviously believe that there is a great need for alternate wave generation artefacts to help deal with (ie destroy) resistance following the satellite's launch. Think of this as a powerful weapon, such as a neutron bomb that can be harnessed and aimed at certain targets.
Email: "Grail - We are removing the Grail from our list of objectives. There is insufficient evidence to confirm its existence. Current examination of Subject Seventeen indicates that aside from the Piece of Eden, all other artefacts related to Christ-figure are literary devices (or derived from Piece of Eden) and not actual objects. Even if the object is real, its use to us at this stage is negligible. Our resources are better used elsewhere."
Explanation: In what's likely to be Abstergo's biggest mistake they decide to stop searching for the Holy Grail. Why is this a mistake? It's likely that this artefact does exist, and that Desmond and the Assassins will track it down and use it against Abstergo in the future. It's possible that Subject Sixteen knew the location and provided clues for Desmond to follow - knowing that Abstergo wouldn't look for its locations while they were so focused on the Piece of Eden. If this is true then Abstergo have underestimated the Grail's significance - 16 obviously believed it was a key artefact in the battle against Abstergo.
Email: "Mitchell-Hedges Communicators - Analysis of the objects is complete. The good news is that they work. As a result we now have a safe and secure communication channel for use after the launch. However, they are severely limited in number, and so we will be providing them only to our most essential facilities. You will obviously retain possession of the one you have."
Explanation: The Mitchell-Hedges communicators are possibly the most interesting items mentioned. Found in a ruined Mayan temple in Belize at around 1926 the 'communicators' are ancient crystal skulls, and there are believed to be only 13 skulls worldwide. The origin of these skulls is unknown, but they are rumoured to bestow the holder with scrying powers - ie the ability to communicate psychically. Abstergo have located these skulls, and it will allow their top facilities to communicate with one another without fear of the Assassins listening in. The mythology of these skulls is interesting: some claim it originated from Atlantis (remember Yonaguni?) at that the Knights Templar carried one about during the crusades. If so, it's likely that it was passed down through the Templars and is now the one in Vidic's possession. That does, however, leave the Mayan relevance in some doubt...