Who created that heavy wound on Sion's chest?

http://3.bp.blogspot.com/-vhxsV91WqUk/VCNLQ9D4P4I/AAAAAAAAZVU/GzQQGYuDLAA/s1600/Sion_Splash_0.jpg

See that large gash starting from his left shoulder all way down to his right hip. Given that he killed Jarvan I/II (who knows which one) it seems unlikely that Jarvan ? would give him that wound. So who did? (It's obvious that this wound is what killed him in his charge.)