I believe this is a 138L Bowie Hunter.
There were several varients of the basic H-15 pattern, and also the Imperial versions. Some of the parts for the Schrade Waldens were actually produced by and purchased from Imperial.
All of the variants were adapted from the MIL-K-8662 (AER) Pilot Survival Knife (16 October 1953 until 1957). Schrade won a bid in 1956 on 23,787 of this pattern knives for the Navy. The cost with sheath was ... $1.196 each. This last info from Frank Trzaska.
Both Imperial and SW variants can be found with pommels and guards of aluminum, stainless, or carbon steel. And the pommel attachment means varies as well. The civilian knives would never meet Mil-Spec in this regard.
The #138 "Bowie Hunter" had a 9 3/4" overall length, a saber ground carbon steel 5 1/8" clip point blade, leather washer handle with spacers, curved aluminum bowie style guard, and aluminum flat pommel. This pattern was a varient of the H-15. It was cataloged in1957, two years before the introduction of the H-15. It listed for $3.95 in 1962. 1973 ½ was the last year for this pattern, and it listed for $8.00. Your knife might well be stainless. Many of these were sold to Sears with an etch on the blade and the red spacers.
Sears # 628 - SW 138 Fixed Blade (1960)
Sears # 10628 - SW 138 (1964)
Sears # 21639 - SW 138L (1967)
Sears # 21649 - SW 138GSB (1971)
Sears # 73613 - SW 138GSB (1972-77)