Toke jopic is toke jopic, but on a serious note, while the drawing make no sense I think the artist somewhat wanted to capture the feeling of the guys' sense of isolation and impotence that the texts they leave behind evokes. You sort of imagine them dying alone without a chance to fight back, and pierced by many wounds. It's somewhat unimaginative, but I think the artist's idea was that of portraying the knights being overwhelmed and butchered without having to draw horrible wounds that could have hampered the game's rating.
Arrow wounds are very clean, and very effective. Look at Boromir's death scene: it's fundamentally an execution, but having it done by arrows (instead of having him chopped to pieces with melee weapons) preserves the dramatic impact without making the scene a gorefest.