I have to legally change my name to Shimp :(

I don't think he was saying he thinks that killing is easy for Wolfwood in that scene, I don't think that's what he meant by "giving up", but rather that Wolfwood gives up on himself too easily, specifically he gives up on his own potential to change for the better and stop being a killer. And yeah, Wolfwood does in fact do that at that point in the series, he has plenty of internal monologues about how he feels irredeemably stained by his sins and can't be anything but a killer. He also often projects these feelings towards himself onto humanity as a whole. It takes quite some time for him to actually start thinking that he's capable of making that choice for himself, that humanity by extension is capable of it, and it takes him WORK to get to that point.

For someone in Wolfwood's position it WOULD be easier, understandably, to think that little of himself, because he's been conditioned to think that way for most of his life. And he has pretty significant motivation to keep killing to protect the orphanage, heck to protect Vash as well. I highly doubt Vash looks down on him for it, he just hates that it's how Wolfwood feels about himself. And I think it's a mark of Wolfwood's determination and strength that he does manage to get to the point of not giving up on himself anymore after everything he's been through, even if he ends up dying for it. He worked hard for the peace of mind he managed to attain by the end, and he successfully saves Livio because of that determination.

cephalophore noun (greek, lit. 'head-carrier')

A saint who is generally depicted carrying their severed head. In Christian art, this was usually meant to signify that the subject in question had been martyred by beheading.