Love the camo pattern on the "Gunner". That is very cool. Nice to see some creative thought processes as opposed to black blades, shiny blades, matte blades, chrome blades, blahblahblah.
I'm jumping a Tactical Tailor chest harness these days. I like way better than the old H-harness LBE or the newer combat vest rig they issued. Logan at Tac-Tailor really got the package right with their chest harness and it gets better with the direct input coming back from the operators using this rig in the field the world over these days.
You have to get the model with the dual buckle system up front. When jumping the new chutes the chest rig must be opened up (unbuckled in the front) to allow the chest strap on the parachute harness to comfortably hook up / fit. The rig is slipped through the para-harness on both sides and then the harness is cinched down. Although it appears the T-T chest rig might flap a bit in the breeze once you exit the aircraft I did not experience this. I'm packing 1 quart canteens in the drop pouches which sit just below my arm pits when wearing my rig. I believe the water weight holds the rig steady during exit / opening. The rest of the pouches running across the front of the rig were likewise packed and secured using the cinch down ties and velcro retainers for each pouch. Nothing was lost or came loose / free during exit, opening shock, or landing.
This is a very comfortable rig to jump and all the weight is evenly distributed on your shoulders, back muscles, and chest. Plus, you can get to what you need FAST, even while still in the harness. I understand some operators elect to strap the rig over their rucks and jump them in this way. I don't see why given my experience, and I wouldn't like to see the ruck impact on the rig during landing given what might get roughed up in or on the rig. Plus, I like my harness/rig right there in case the DZ sucks something fierce, or if I have to cut the ruck away due to an inflight emergency.
Knifewise you can jump a blade in a hard plastic or Kydex sheath system off the old style LBE pistol belt / combat vest without much trouble. I'm working on how to affix my SF Command from TOPS to the T-T rig so the knife is riding with me on the combat harness during a drop. Normally you want nothing on your pants belt when jumping in, and most often many of us "old guys" tuck the fatigue shirt into the pants and cinch the pants belt down prior to putting on the chute.
If you elect to jump a knife in that, for whatever reason, can be attached to the LBE rig then pack it either on top of everything else in the ruck so you can pull it out fast upon landing, or pack it in an outside ruck pouch / pocket for the same reason. However, ensure you can cinch down and/or tie the outside pocket TIGHT as opening shock will rip the crap right out of a poorly secured outside pouch. Remember the ruck is riding in the harness upside down and when lowered it will come to a sudden stop once the lowering line is fully extended. You find lots of neat things on a DZ after a few drops because of badly packed and secured ruck pockets.
I know guys who will pack a medium size sheath knife in their pants cargo pocket, then attach to belt or harness once on the ground. Again, make sure the pocket is secure and be prepared to land atop the knife/sheath while doing a PLF (parachute landing fall). That could hurt bad...
The T-T with a long drop pouch mounted along your sides underneath the arm pit(s) would work fine for dropping the sheath knife into and recovering once on the ground and safe. Further, if you get hung up or need it for whatever reason it's there and handy as opposed to wrapped up ass-backwards on a pistol belt, or stuffed in your rucksack.
As always, safety first. If the rigger or jumpmaster says "no go", it ain't going.