I would use that capsule to store fire related stuff myself. Some tinder, maybe a small striker made from a cut down hacksaw blade, "never blow out" birthday candle, matches, etc. I don't know how big that capsule is so I don't know if all that stuff would fit.

Your survival kit should be something more than just the capsule on the end of a firesteel. Store your regular sized mirror, whistle, compass, etc. in that separate kit.