Guan Yu is wounded by an arrow, but it wasn't a bad injury

But the fact was that Pang De had only pretended to try for a foul stroke in order to cover a resort to his bow. He pulled in his horse, fitted an arrow to the string, and was just on the point of shooting when Guan Ping, who was sharp-eyed, shouted out a warning.

"The bandit is going to shoot!"

Guan Yu saw it, but the bowstring twanged, and the arrow came flying. He was not nimble enough to avoid it, and it wounded his left arm. Guan Ping at once went to his father's assistance and led him away to the camp. Pang De wished to follow up this advantage and came back whirling his sword, but, ere he could strike, the gongs of his own side rang out. He thought there was something amiss in the rear and stopped.

...

Guan Yu went back to camp, and the arrow-head was puled out of the wound. Happily it had not penetrated very deeply, and the usual remedies against injuries by metal were applied.

Guan Yu was very bitter against his enemy and declared, "I swear I will have my revenge for this arrow."

"Never mind anything but recovering now," said his officers. "Rest and get well; then you may fight again.

Before long, Pang De renewed his challenge, and Guan Yu was for going out to fight; however, he yielded to the entreaties of his officers. And when Pang De set his soldiers to reviling the warrior, Guan Ping saw to it that his father never heard it. After ten days of challenges hurled uselessly at an army that ignored them, Pang De took council with Yu Jin (Romance of the Three Kingdoms, Ch 74).