I saw someone using an axe handle last week. Bats and 2 x 2s as well. Not saying you need to use those. I have a paint roller handle that my husband found in the basement.

Half inch steel pipe with holes drilled in it, zip tie the flag. or other equally sturdy pipe. It may get very windy. Naturally, using such a heavy sturdy thing as a weapon would be highly antisocial. I am sure you would never use it that way, especially against knees, elbows or ankles ;-). Or as a lance to testicles either....

I suggest you also bring lots of extra spare calf length black fruit of the loom athletic socks. To keep your feet warm. And to carry your lunch--chili cans, canned fruit. And a nice sturdy fork and BIG can opener for eating lunch with.

If you lack socks, you can use a heavy cloth tote bag, dark colored.

Obviously, be very careful not to swing your lunch exuberantly or indiscriminately, as you could really hurt someone. And if you happen to get blood on your socks or bag, be sure to properly dispose of them in a trash can. Littering is not nice ;-).

1/2" iron pipe home depot plumbing section. Drill two holes and wire tie flag.

Bats make good flag poles

I've used some PVC pipe and zip ties, fairly inexpensive.

Homedepot sells aluminum tubing, I’ve used it to make target stands as well as forms to outline a brick patio. You’ll need a hacksaw to cut it to length. Duct tape could be used to make/form “palm swells” to hold it comfortably for long periods of time