Just my 2 cents, which because of inflation holds even LESS merit.

Blade NO MORE than 4 inches from point to handle (many places have a 3 1/2) restriction.

Like Spidy said, false top edge for legality. (They CAN be sharpened though)

Bowie style blade (no radical upswept point)

Good res c handle with strategic swells and sways for extra grippiness.

NO TOP GUARD, and a minimal bottom guard.
IF it's gonna be a BOOT or Waistband blade, you want to be able to bring it into play with as small a chance of it grabbing something on the way out as possible.

Full flat ground blade and as Spidy indicated no choil. BUT a small round Cutout, maybe 1/8 inch so the full length of the cutting edge could be sharpened.

Actually I think that the 311 handle would be fantastic on this blade. It's small thereby enhancing concealability, yet large enough to get a good grip on(although a possibly 1/2 inch longer would work also). It's Res-c so there is a grippiness without being overly grippy.

Actually, being Res-c IF the blade side of the handle were designed with a swelling out of the handle, an actual guard might not be necessary.

Oh well, just my thoughts.