An arrow.

When you send a line it’s like sending an arrow.

You could send that arrow right through the other character and out the other side and stick it into a wall ten feet behind.

Or you could send the arrow just to their chest, letting it stick there… hurting.

How do you draw back the bow? Rapidly, like a warrior? , or slow and deliberately? Is it your first time shooting an arrow? Are you a warrior? 

What tip do you have on the arrow? Is it poisoned, or an ancient stone tip? Is it high-grade steel, thin and razor-sharp, serrated?

Or:
‘Cupid draw back your bow
And let your arrow go
Straight to my lover's heart…’

See it. See what you mean, want and how you send it.

You must play sharply. That’s how we live - like a series of very specific arrows shot from very definite bows by archers each with their own intent.

 ‘I go, I go; look how I go,   
Swifter than an arrow from the Tartar's bow.’