Skyrim V: Skyrim

[Rake21]

I have two questions:
Firstly, is there any reason why whiterun guards and Alvor would immediately start attacking Gerdur? I ask because in the middle of the day while I was smithing, they murdered her for no reason. Then ten minutes later a courier sent me a letter from the Jarl of Whiterun giving me his condolences.

Secondly, what does it mean if your Imperial Bow has a green arrow icon on its name when its in the inventory?

Apparently, Gerdur can go into frenzy sometimes when you fast travel. She becomes hostile and the guards stab her until she stops moving.

As for the bow, no clue.