Is it known why the Western W36 had so many blade shapes and handle variations?
As with any thing in sales, any variations were an attempt to catch the eye of a different buyer and sell more knives.
That being said, the 36 pattern actually only had 1 blade shape through out its 70 production history, 1936 - 2006 --- a 5-1/2" clip point blade. If the blade has a length of anything other than 5-1/2" or a profile of anything other than a straight back spine with a clip point, it is NOT a 36. Broken tip re-profiles excepted
The 36 pattern variations were all handle material, pommel shape or guard shape related.
Stacked leather handles (L36K/L36KG/L36) 1936 to 1972
and then
Wood handles (W36) 197x to 2006.
The production specs of the 36 pattern by period are :::
1936-1940 version came as either a half guard/bird beak pommel or a S-guard/flat brass plate pommel
L36K 5-1/2” clip point blade / half-guard / bird beak pommel
and
L36 5-1/2” clip point blade – flat brass pommel plate – S’ guard SEE tongueriver's post top left group of 4 - 3rd knife down
1941 version - only 1 pommel type, but 2 guard styles
L36K -1/2” clip point blade / half-guard / bird beak pommel
and
L36KG – 5-1/2” clip point blade / bird beak pommels / s-guard See tongueriver's post above top left group of 4 4th knife down
1945 – 1958 version
L36K – 5-1/2” clip point blade / half-guard / bird beak pommel
1959 – 1972 version
L36 - 1/2” clip point blade / half-guard / bird beak pommel
1968 – 1972 version
L36 - 5-1/2” clip point blade / half-guard / bird beak pommel
1973 – 1976 version
W36 - 5-1/2” clip point blade / half-guard / bird beak pommel
1978 – 1991 version
W36 - 5-1/2” clip point blade / half-guard / calf's foot pommel
1992 – 2006 Camillus version - threaded pommel - not double pin tang
W36 - 5-1/2” clip point blade / half-guard / calf's foot pommel