I was also unbelievably lucky that my farrier showed up while I was on the phone with the vet. Within 10 seconds he was able to diagnose an abscess which saved me a long trip across town and a vet bill. He was able to make such a quick diagnosis because he had hoof testers and a hoof knife at his finger tips. I'll give you a quick guess as to what now resides in my med kit.
Not wanting to be a total chick about my new tool, I cut away the wrapper and actually made sure I knew how to use it before a crisis strikes. I poked around at both Speedy's and Izzy's hooves trying to determine just how hard I need to squeeze. I eventually realized that I can squeeze as hard as I can without getting a reaction on a healthy hoof.
You'll notice that I also bought a hoof knife. It's a fairly cheap one, but again, I don't plan on needing it very often. It's a stainless steel, double edged knife that feels good in my hand. It seems sharp, but I didn't test it out. I actually hope I never need to use it. At $3.95, it's practically disposable anyway.
Here's to hoping that neither of my horses ever abscesses again, but if they do, I am armed and ready!