騏 is a variant of 麒 or 驥. Hence 天 騏 may refer to the 麒麟 (The Chinese unicorn and not the Japanese Kirin (giraffe). When the first giraffe was brought back to China from the voyages of Admiral Cheng Ho, to flatter the emperor, they deemed it as the kirin to flatter the Chinese Emperor. The appearance of the unicorn signifies the proper rule of the emperor who had usurped the throne of his nephew and thus validates his legitimacy. So the meaning can be "celestial horse" or "heavenly unicorn".