Dale Maurer is a security consultant.
That's what his business card would indicate since it states "RONIN SECURITY". It helps pay the bills.
More people would think of him as a martial arts instructor. That is how most people see him and what he enjoys doing when he is not putting his neck into a noose, which seems to be quite often. Since he does the self-endangering to help others who cannot help themselves, though, he is seen for the hero he is, not a thrill-seeker. He might earn a living as a security consultant but in truth he would do what he does for free.
Maurer likes to think of himself as a Ronin. As mentioned in the opening pages of the first adventure, Maurer "is a student of the samurai, the medieval Japanese warriors. Most of the samurai pledged loyalty to a feudal lord, just as the western knights did in medieval Europe. Either by fate or by choice, some samurai found themselves without a master. These were known in Japanese as the ronin. A ronin could use his fighting skills as a mercenary, or as a bandit, or to help the common people-employing his martial prowess to provide justice, when no one else was willing or able to do so. These latter ronin were described by a Japanese word that translates as 'street knights'."
As one of these street knights, Maurer is not a spy by any means but since the people he goes up against prove to be international in nature, he might as well be especially since he spends so much of his time helping out his best friend from his military days in Afghanistan, , who shortly after the series starts gets deeply involved with fighting terrorists, both foreign and domestic. The relationship between Maurer and Wei is a bond closer than brotherhood as they both like helping and they both detest bullies and they both love a good adventure.
Maurer is, when we first meet him, 36 years old but his looks routinely deceive people. He is said to have a baby face, looking far younger than he is while at the same time he prematurely has silver hair giving him the appearance from a distance of someone far older.
Some people say they are a 'lover, not a fighter' but Maurer would probably claim to be both, and be right.