Luciel

The reason she said this is that she had no control over the attack. 

For example, normally she would modify the ice shard into something like drill bits before shooting it out.

She also gave some spin on the projectile to enhance the speed and damage.

But with this one, there was nothing she could do, making it useless in a real fight between cultivators.

Even the mana gun from Alex's world do more damage, and more useful than this.

"You're right if it's in a direct fight. But if we mix this with rune, it will give us a lot of possibilities," Alex had learned some basic runes from Vesa, but none of it was useful in their current situation.

Now, if he combined it with the gemstone, he could make something very destructive. 

The area around them was filled with life force as long as he used a rune to absorb and point it toward the gemstone, then added some mechanism to target the attack, it would be like a turret with infinite ammo.