Here is a smartphone case that doubles as a sheath for a 6.5″ EDC knife that you can carry with you everywhere. The Burls Signature Phone Knife Case is made with leather hand sewn with high strength thread. It comes with a snapping blade strap and belt clip.
This phone knife case should handle most phone brands, even with a hard shell case. The knife has a 2.5″ AEB-L stainless steel blade. It has a Bocote exotic hardwood or Richlite handle (your choice). You can get yours on Etsy.