My Sheath pouch contains a slim perspex case (originally containing a bicycles puncture repair kit!), a good tight coil of strong nylon cord & a mini LED torch.
The perpex case contains, spark-rite, vaseline/cotton balls, scalpel, puritabs, bic lighter, 25metres dental floss, fishing kit, sewing kit, tyre patch glue, button compass, slim (homemade!) mirror, lens, magic birthday cake candle. I can just about slide a space blanket behind all the kit in the pouch, and I have about 10ft of paracord wrapped around the base of the sheath, too.
I havent put anything inside the handle as yet, but it will probably be more firestarting "stuff"!

Im working on a pouch to go on my battle rat when it arrives, made from a Garmin GPS pouch, I believe the pouch is virtually identical to the BK & T sheath.
A British Army magazine pouch (holds two SA80/M16 mags!) also fits quite nicely on the front of the sheath, though it IS a little on the large side!