Shadowmarks are secret codes and symbols used by underground organizations and actors. Only Thieves are able to know these symbols offhand—others must learn their meaning from a Thief.
Weapons Cache
This mark denotes a container or crate that is designated to be a safe place to find a weapon for use in a pinch... Or to possibly hide a weapon that could implicate someone in a crime...
Healer
Oftentimes, a morally ambiguous individual will be injured in their line of work, and in such times most healers would likely report them to the local authorities. This particular symbol indicates a place where questions of legality are seldom asked during the healing process.
Dead Drop
This mark specifies a place where a thief can leave some ill-gotten loot, or some information that would be useful to a higher-up in the criminal community.
Safehouse
When things run afoul during a heist or other such questionable activity, it is common for a thief to be unable to escape to their hideout. In these times it is best for them to have a place to lay low. This mark denotes such a place where a fugitive can be reasonably safe from the law, provided they take the proper precautions.