Definition of "unknightly"

There still faintly beamed from the woman's features something of the freshness, and even the prettiness, of her youth; rendering it probable that the personal charms which Tess could boast of were in main part her mother's gift, and therefore unknightly, unhistorical.

1891, Thomas Hardy, Tess of the d'Urbervilles, volume 1, London: James R. Osgood, McIlvaine and Co., page 31