So, yeah, then this happened. Given the trivial availability of guns in Baltimore City, my guess this guy wasn't wielding a flail because he couldn't get a piece; it's interesting that the attacker apparently struck the intended victim and then made a demand that he turn over his phone.
According to a police report, the man said he was sitting in the grass in Patterson Park next to the baseball field on Thursday night at about 8 p.m. when four juveniles, about 14 to 16 years old, came up to him.
One of them was wielding a "ball and chain," and struck him in the face as the others stood by, the report says. The weapon is called a "mace" in the report but could also be referred to as a flail.