If gabriel can be killed with a एंजल blade why cant lucifer i know this is a old सवाल

Lucifer probably could have been killed using an एंजल या archangel blade, but no one thought of using one against him.

it could be that he was an एंजल but he have become a demon so he might be a dangel now and an एंजल blade won't kill him

He's pretty damn fast and strong. Gabriel was an archangel and still couldn't beat him, maybe Micheal could though. Having the blade doesn't mean आप can get a hit in. It wouldn't be as easy as with Zachariah.

Normal एंजल blades don't work on Archangels so they have special blades (Archangel Blades) that can kill other एंन्जल्स but are the only thing that can kill each other. Lucifer cannot be killed with one of the normal एंजल blades since he is an Archangel and he used his Archangel blade to kill Gabriel. (don't worry I thought about this a lot when I first watched Supernatural)

Gabriel wasn't killed with an एंजल Blade he was killed with his own Archangel Blade which is और powerful and rare to come द्वारा since only Archangels possess them.

I think it's because certain fallen एंन्जल्स can't be killed , like Lucifer.