Durge - Samurai Jack

Durge would never be defeated, as, magic sword or not, if there's still organic material left of Durge, he can, and will recover. It's due to his species.
The Gen'Dai have ridiculous regenerative properties, which also lead to a longer lifespan. Durge had been active as a bounty hunter for two thousand years. They lack bones, hearts and lungs, and can regrow new body parts should they lose them.
In addition, the Gen'Dai have virtually instantaneous reaction, extremely acute senses, and could recover from severe injuries which would kill any other species. However, they could be put into a state of hibernation if they suffer enough bodily damage, as they wait to recover. The only known way to kill a Gen'Dai is to vapourize or incinerate the entire body.
But the only part of their body they couldn't regenerate is their brain, which meant that it was subject to deterioration over time, inducing a state of psychosis in older individuals, such as in Durge's case.
The actual culture of the Gen'Dai is pacifistic, save for the case of the elderly, who would become more violent.

That said, I don't think Durge would defeat Jack, as he has been through hell and back in the future, and always seems to prevail, whether it be alone or with someone's help. Durge would certainly be able to give him hell, but would never truly kill or otherwise defeat him.

Gen'Dai page

As for the artistic difference between the two images presented, you should go with the lines. It adds more to him visually.