A little two-part response today- apologies for how long it took me to respond to these:
1. The silver ring with black stone Dylan wears does not seems to have any significance, other than any superficial dark or gothic aspects it might have. It was mentioned in many reports, including his autopsy, without further note.
2. As for the “Arsenal of Freedom”- this phrase about his bedroom is simply referring to the fact that they kept their weapons (“arsenal”) there. Based on the FBI report of their tapes, it seems that Harris and Klebold filmed in Harris’ room when they were showing off their weapons. They filmed in a variety of other locations, including Harris’ basement (but also Harris’ family room, Klebold’s room, and in a car), when discussing their plans for the attack and personal philosophies.
Colombinus 