It sounds like they will be waiting but they'll never quite finish.
Adorn atop shoulders they will define me, break me and finish me.
I can be deadly, creative or destructive.
I get speared through the middle but it's more helpful than harmful.
I am a mark of new beginnings and can be a sign of rebirth.
What am I?
The first and seconds lines are one clue but must be done bit by bit one before the other.
Lines 1+2 give a clue to the word structure and 3-5 for what the word is.