User blog comment:KnocknickKnock/9 gates + master of the celestial realm/@comment-24066070-20131208182752/@comment-7418318-20131212213223

I'm not so sure Caelum is so parfect. Sure it's versatile with both ranged and close combat forms but both shapes have the same disadvantage: speed. In it's sword-form it's big and comparetively unwieldy, which makes it less than ideal for dueling another close-combat wielding opponent. And the shot in the cannon-form, while packing quite a punch, has a long charge-up time, which pretty much relegates it to surprise attacks and long-distance sniping.

Also we should keep in mind that Angel was stronger (and less exhausted and hurt) than Lucy when they fought. With the strength of the spirit depending on the summoner, who can tell how much damage the shot would have done if Loke had been summoned by someone of equal power as Angel.