Twinkling and shining like a star in the sky, laughing and crying - but who am I?

Question

The words on the page
Arranged in neat lines
Like a play on a stage
When done well - there I shine.

On joyful, bright days
And downcast, sad ones too
When you meet someone's gaze
I'll be there, clear and true.

Anger burns and flares out
And I'm there in the hurt
If you yell, scream, and shout
I wipe away dust and dirt.

Like the slow patter of rain
Or ebbing waves like the sea
Coming fast like a train
Or quietly sitting, like a nice cup of tea.

There are some who misuse me
Teeth as sharp as a knife.
But you do really need me
I'm the salt (not the spice) in your salad of life.

When you've lost something dear
I'm there like a friend
You have nothing to fear
After all, I might be a good thing, in the end.

Who am I?

Answer 1

I think you might be

a tear (- and a nice poem aswell).

When done well - there I shine.

A good book or play can create emotions and so tears (joyful or painful).

I wipe away dust and dirt.

Tears kind of wash your face.

Coming fast like a train or quietly sitting, like a nice cup of tea.

Crying out loud or just let a single teardrop appear in your eye.

I'm the salt (not the spice) in your salad of life.

you are indeed salty.

Answer 2

Is it

your eyes?

Explanation:

Your eyes shine whenever you do something well.
Your eyes meet another's gaze.
Your eyelashes keep out dirt and dust.