I think you've got it. Rather than hash the message out in IC, let's hash it out here and I can post a simple "after some back and forth, the group agreed on the following message" type IC.
To whom it may concern,
Attached to this message you will find some images of an ancient artifact of unknown providence. This was discovered near [location] by archaeologists working for the Atlantean Foundation. While I believe that the organization as a whole may be true of purpose, the researchers assigned to this artifact were corrupted by unknown outside parties. I, along with some others, came to be employed by one of these parties to steal the artifact for their own nefarious purposes. Unbeknownst to us, Ares had its own designs on the obelisk, and through a series of events that I shall not recount, we have joined together and decided that the largest amount of good could come from neither of our previous employers obtaining the item.
After some consideration, we have decided that your organization would provide the safest and most productive home for the item, and so offer you first right of refusal. The attached photos should pique your interest, but images can be forged. To that end, we have also taken a spectral photograph of the object. The material content alone is worth millions, but the raw magical power of the item apparent in the quicksilver image makes the item priceless.
The quicksilver plate is at [location]. The location is public so as to ensure this is not a trap and to reduce the risk to both parties - it costs you little to verify my claim. Once you have been satisfied that my offer is legitimate, please forward this message and the plate to [person] and have her contact this commlink. We will only deal with her. We will arrange a time and location for the exchange as well as the terms. As the item is wanted by a number of powerful organizations, you can understand our need for caution and urgency, and we are prepared to make a very attractive offer to achieve those ends.
If we do not hear from [person] by [deadline], we will be forced to assume a lack of interest and we will shop our offer elsewhere.
Once we have the message finalized, Ohanzee will summon Torchbearer and have him deliver it to our selected location, as well as escort him from the astral just in case anything goes awry. He will hang back so it is not apparent from casual observation that they are travelling together and he will remain at a distance when the item is placed so that his aura is unlikely to be observed. He will likely do this from town just so that his location can't be traced back top the camp should it come to that.