Disarm him of his, and use that
Okay, okay, for real I like TRAINING with the arnis stick, as it can be just about anything.
But, as for my personal preference of arms, I like the telescoping baton. Don't know if it counts, but it's basically an arnis stick that I can keep on me without a) drawing attention b) small and relatively lightweight.
I live near Chicago (predicatbly), and since I know I will be moving there someday(and I don't exactly posses the "imposing" body-type) I figure I will procure one sooner or later.
One thing I DO NOT like seeing people with however, is a knife. It's not a "self-defense" weapon, it's a combat weapon. Combat in that, your intent is not to restrain/halt you offender, so much as it is maim/kill him when you take out something sharp. Way to messy, plus invites a lawsuit on your hide whe the guys gets outta the hospital. Not fun at all.
Then, there's the whole "But officer, he came at me first! If he didn't lose all that blood, he could TOTALLY back me up on that." problem, too.
I could see knife, but only if you live in a REALLY bad place and need THAT kind of protection.
By the way, HILARIOUS use of the old emoticons. Love that creative flair.