Board Thread:Questions and Answers/@comment-31516341-20170619120207/@comment-918376-20170623025642

Royal Guard Landers outside their suits don't announce they're off-duty Royal Guards. In the anime, Enbart Nelles is seen walking around before he buys the cursed sword and nobody knows that he's one of the Guard until he starts going on a rampage and people start connecting the dots.

Long story short, to go back to your original question, your assumption is that Royal Guards are another separate type of Lander. They're not, they're the same as Rayneshia or Kinjo or Sara. It's just that they act differently when they're on duty, and it just so happens that Enbart Nelles was pissed about his situation where others weren't.