Our first sessions saw a major battle in the castle Bhualin. The fight with the Faith-Stealer Golem as well as the augmented undead went fairly well (and there was that weird sand guy...). Through scouting of the ancient castle you were able to get where the undead had not.
As you discovered in the books, the Imaskari were an ancient humanoid race that lived thousands of years ago. They were primarily artificers and were fascinated by extra-dimensional spaces, as well as planar travel.
The Imaskari used their vast magical powers to open a rift and steal humanoids from other dimension to use as slaves. Over time the humanoid slaves are generally referred to as the "Mulan" race.
The Imaskari developed artifacts to seperate the Mulan deities from their people, eventually they created artifacts called "The Imaskarcana" That allowed them to kill the mulan gods, the last of which was Horus.
There were seven Imaskarcana made. The exact description of what they do is not in any of the three books. However it seems that all were designed to limit or destroy divine presence and divine magic. If a user tried to activate any of the artifacts abilities in a language other than imaskari they would pay a dire price.
That is a summary of all of the relevent knowledge you gain from the books.
Bobby mentioned a teleport protocol to sell your un-needed items. Here are some things to think about:
The Rod of Lordly Might will attract attention, it shouldn't be too difficult to sell in a larger city but they may have quesions. You may also attract treasure hunters or thieves.
The artifact sword that Aen has in his possession is indeed one of the Imaskarcana. To someone with no magical insight it appears to be just a fancy sword. Anyone with any magical aptitude will be able to tell that the sword is an artifact even without using a detect magic spell. Any divine magic user will automatically have an unfriendly attitude towards the welder unless they know them personally. From what you can tell right now divine magic has a muted affect on the sword. However you have yet to ascertain what abilities (if any) the artifact posesses.
It will be difficult to bring that sword into a large city without causing problems. There is also a good chance that now that the sword is out in the open it may attract divine attention.
If you want to teleport before the session on this wed that is fine, but let me know how you are going to do it here (I got the technical aspect, but are you going to take everyone, split up, hide the artifact, take it with.). Let me know your plan and I will work out if anything too crazy happens.