You will do me a great favor, though, if you guide me to a MEDIUM sized messenger bag (5 to 7 liters size / 300 to 400 cubic inches) without padding and with an admin/organizer pocket. It should NOT be tactical, but definietley manly.
If you don't mind a mildly mitigated (unorganized)shoulder bag in the 300 ci range, there's the Rothco Canvas Ammo Shoulder Bag. Despite it's name, it's more of a mussette than a tactical bag. https://www.rothco.com/product/rothco-canvas-ammo-shoulder-bag
I've found it "just right" for my sunglasses hard case, paper product (planner, notebook, or paperback), spare cell battery, and a small pencil bag. It's not the highest quality around. But, for $11 and a couple minutes with needle and thread reinforcing the stress points, it's hard to beat the value.
Incidentally, 5-7 liters is considered a small to x-small messenger or courier bag. Medium is closer to 15 liters. IMHO, vertical messengers and dedicated courier bags are more comfortable cross body than the horizontal messengers.
EDIT: The style known as "American Heritage" which is all canvas, leather, and brass hardware constructions meets the "Manly but not Tactical" requirement. The stuff looks like it was left over from WWI