This is the Oxford Dictionary's definition of literary:

(of language) associated with literary works or other formal writing; having a marked style intended to create a particular emotional effect.

The use of archaic words is one way to create a particular emotional effect. It is, however, just one of the possible ways- one that is probably only suited to historical novels. At the opposite extreme, George Orwell used neologisms to great literary effect in 1984.

Use in other kinds of documents? Of course... for a fusty government report, you use words that create a suitably fusty emotional effect.

This is the Oxford Dictionary's definition of literary:

(of language) associated with literary works or other formal writing; having a marked style intended to create a particular emotional effect.

The use of archaic words is one way to create a particular emotional effect. It is, however, just one of the possible ways to create one particular style: a style that is probably only suited to historical novels. At the opposite extreme, George Orwell used neologisms to great literary effect in 1984.

Use in other kinds of documents? Of course... for a fusty government report, you use words that create a suitably fusty emotional effect.