[Does Sebastian think he can go about fighting with a few scythes sticking out of his chest? Sebastian is the kind of person who thinks he can defeat a Reaper with a butter knife. Of course he thinks he could fight regardless of the number of scytches sticking out of him. You see:]
I will not leave you. [He won't die, in other words.] And, as per our contract, I will keep you safe no matter the circumstances and no matter what injury I might suffer. [......Sebastian. Sebastian, in Ciel's timeline you were unconscious. Twice over, even, brief as both instances were. Still. Unconscious.
In Sebastian's defense, he knows he has limits. But if Ciel is in danger Sebastian has to protect him regardless of where his limits lie, regardless of how injured he might be. There is no alternative to that - he'd simply have to find a way to do it.
And while he answers Ciel this time, Sebastian is still listening to whatever the voice in the device is saying (it can hardly be called multitasking when he's only focusing on two things at the same time), frowning lightly as he does.]
This is how it's meant to be worn, I think - rather like a tiara. [He holds out the second device for Ciel. It's just a voice - nothing more dangerous than that, it seems.] Please put it on.