hmm... my guess is Sting.
a "cold hard" sword that frodo/bilbo used as a "protector" often.
It, at times, "preserved the ring-bearer" (Frodo,Bilbo) from the "former ring-wearer" Gollum. He was scared of the blade and respected its carrier hehe
And Sting saw lots of action, ("was struck") but never broke.
There you have it haha