It's not unknown in real life for prisoners to become guards. It happened in the Nazi system (the "kapos") and in the Soviet Gulag system as well. And there used to be US prisons that used "trusties" as guards until they were shut down because of gross abuse. Go to Comment
Why would a prisoner (accused of murder) become a guard? Why not just escape? What kind of "odd jobs" can a prisoner do to earn money from guards? Alot of this doesn't make much sense. I could see him bribing the guards to leave a gate or two open, but that is about it. Go to Comment
I like weapons of repute with minimal to no magic. In Runebearer ( www.runebearer.com / http://www.cs.cmu.edu/~tpope/bostonia/frameset.html and a shout out to Chris Magoun who is a member here), weapons gain in power as their stories/ legends grow and wielders learn more of the item's history.
However spellish magic is not required. It is all about the reputation here. And that can be the greatest magic of all. Added to Interesting Weapons- Non-Magic While it is not a "class of weapons" as normally is the case for that submission, it is clearly appropriate.
This weapon, even if you don't use it directly, serves as a great example for your own world. It shows the power of reputation. Go to Comment