trim on Andersen casement window

Looks like you definitely need new trim, I'm just not sure if this is something we can help with. Can you tell me the function of this trim? Does it keep the weather out, or does it hold the glass in the frame?

Could you also remove a small sample and show me a clear picture of its end profile? That will allow us to make out the shape, which is an essential detail. I know that the trim is brittle and falling apart but please try your best to show us a sample that is as undamaged as possible. We won't be able to ID it if it is too broken up.