It's one of those series where the MC is unjustly kicked out of his party, but here he retires and gets a job as a city guard. I've forgotten the title and have been trying to find it for a long time.
It is not Labyrinth Raids of the Ultimate Tank, I thought it was, but it is not what I'm looking for.
It is a setting with monsters, magic, and job classes. The MC is your standard aloof black haired protagonist. His old party leader used a spear, was an arrogant jerk, and replaced him with a woman. The entire party was based around offense with no defense and quickly find themselves doing terribly without the MC. In one of the early chapters, he is tested by defending some kind of orb from three other guards who are jerks themselves. And the images are black and white.