Looking at the pics, Whitebeard is stabbed in the abdomen area, not the chest.
It's about time somebody wounds the old fart. I really like how it was a traitor of all people that injured him first. Gotta love the conniving bastards
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From here on now, everything goes downhill for Whitebeard. His incessant bleeding is going to greatly affect how well he'll be able to perform in his duels.