Designs for the soul trap
You've thought it prudent to retain the designs for the soul trap you recovered from the Circle of Thorns. It's a reminder of the adventure you like to call:
It all started when Mage Killer Zuhkara asked you to recover a new soul trap from Ghost Widow's faction. The trap should have been working, but for some reason, Ghost Widow was keeping it under lock and key. You got permission from Arbiter Daos and took the soul trap by force.
But it didn't work. Zuhkara sent you to the lab where the trap was originally designed. There, you found that the Circle had invaded the lab and were holding the only working prototype. You dispatched them and recovered the real soul trap.
Mage Killer Zuhkara made some small modifications, then sent you to test the soul trap. It worked just as she intended: wiping out the Circle mages with deadly speed. You have returned the trap to Zuhkara, but held on to the designs. Who knows when they might come in handy?