: Game Theory: Skyrim, On the Subject of Arrows and Knees.
Another theory is quite simple: all the guards got married! This theory is somewhat more plausible than the previous one. Rumor has it, "Taking an arrow in the knee" is Nordic (the main inhabitants of Skyrim are called Nords) slang for getting married. Some have cried foul at this claim because, in viking society, women were highly respected as homemakers. So such a snide comment about how crippling their marriage has been doesn't make much sense. That was until you realize one thing. What happens when your knee gets hit with an arrow? Please stand up for a moment. Okay, good, now stand with your legs about shoulder width apart with your right foot slightly behind you and your left in front of you. Now being careful, gently hit the bend of your right knee. What position are you in now? Are you kneeling? Good. That is what I think this saying means: not a derogatory remark about ones spouse, but the opposite, that you were so in love you fell to you knee like you were hit with an arrow. (I am not responsible for any knee injuries received during the exercise.)
The third and final theory can really only be understood by longtime fans of the Elder Scrolls series. The passing quip of a hold guard may really be Bethesda's way of poking fun at the differences between the armor in the forth installment, Oblivion, and the fifth, Skyrim, mainly the lack of specific knee armor in the latter. This was a cleaver trick on the developers part.
If these theories have anything in common, it is that they are just that: theories. I'm sure I didn't cover all of possible reasons for the rampant arrow-to-the-knee-itis which seems to be plaguing Skyrim's adventurers, but I do believe these are some of the most popular. Please be sure to tell me in the comments which one you think is the most plausible, or even better, tell me any theories you have heard.