Be for warned, I had a few items attached to my zippers in the past. We got to camp 7 miles down the beach in Washington State. I went to pull up my lighter, and it was gone. Not only was the lighter gone, the zipper had broke off it.
Having larger items attached to zippers lends it self to snagging on branches when going through wooded areas. (this is what I suspect happened to mine) If they are on your pack, and you feel resistance, you just pull through, thinking it was just a branch that grabbed on.
In my opinion, I would not hang life saving tools like a fire kit on the outside of my pack.
Best,
Myesque