Skolemization is refutation complete but not validation complete. Means if you have a theory T, and its skolemization T^S, you will know:
T |= [] iff T^S |= [].
This is why skolemization is often found in theorem proving. For validity you would need Herbrandization which will attack forall quantifiers and not existential quantifiers. With Herbrandization one has:
[] |= T iff [] |= T^H
Both Skolemization and Herbrandization are based on the following higher order identity and its dual which can be obtained by negating both sides:
forall x exists y A(x,y) <-> exists f forall x A(x,f(x))
The identity makes use of the axiom of choice in one direction. The quantification of the functorial f is delegated to the signature of the first order theory and the definition of the |= sign.
Possibly Skolemization and Herbrandization can be combined, but I wouldn't confuse it with Morleyization since both Skolemization and Herbrandization introduce function symbols and not relation symbols.