Didn't Know Foil Was A Deadly Weapon

So back on Thanksgiving I was trying to open a bottle of wine.  Covering the cork was this really tight and strong foil that probably had some metal in it.  Now I usually have some trouble cutting this part of a bottle open, and this appeared to be the same pain in the ass.  So I used a small knife attached to the corkscrew to try and cut enough of it to pull and tear off the rest.

But this was a bigger struggle than I thought.  I had only managed to pull up on side of the bottom of the foil to the point where it sort of balled up.  And as I was holding it to figure out an easier way to open the bottle, I inadvertently dragged the tip of my right index finger across this nub of foil -- and it made a cut, a fairly deep cut, on my finger.  I said to myself, "Wow, that kind of hurts!" and then I looked at the cut on my finger that was starting to seep blood.  It wasn't gushing or anything, but I don't remember ever seeing or feeling a cut that deep, nor seeing a cut on my finger like that before.  So I ran my finger under cold water before applying a Band-Aid.

That Band-Aid fell off when I took a shower on Friday, and while it no longer was bleeding, the cut hadn't fully sealed up yet.  There was dead skin surrounding the cut, and I pulled off some of the skin before thinking better of it and putting on another Band-Aid.  This second Band-Aid is still on my finger, and I really don't want to take it off until that cut is fully healed, no dead skin or anything like that.  So I'll wait.

But I couldn't think that foil, even tough foil like that, would be strong enough to cut you.  What the hell?!  I haven't been able to help myself from spacing out to, say, using a cut-open piece of foil like how I eventually was able to open up the bottle (with the help of pliers and, by the way, it is a screw cap and not a cork) as a self-defense weapon in case someone out on the street wants to try something.  I could just take out what seems like a piece of trash and slash the bastard across the arm or the torso, or worse.  Yeah, I've got to stop letting this red mist descend upon me and make me think violent thoughts.