I would say most women are attracted by men with strong arms. Well-developed muscles in men are a sign of sexual fitness. So sorry, it's basic biological attraction and not a fetish.
Surveys and studies suggest the majority of women prefer athletic builds to strong or developed builds, and that an overall balanced or well-proportioned musculature is preferable to a focus on any particular grouping, such as arms, chest or legs. However, it was men who thought that the stronger builds were more attractive.
Fetish definition "any object, part of the body, or activity that is ordinarily regarded as nonsexual and causes a habitual erotic response or fixation."
By either your definition or mine, which says basically the same thing, arms are not considered sexual organs and thus are technically a fetish.
Be sure you're not confusing this with the concept of kink, which requires the attraction/focus to be considered unusual.
Next you'll be telling me men liking boobs is a fetish.
Are boobs now regarded as non-sexual?
This is an interesting point but I don’t think it’s true. Isn’t it just a way for women to show off their painted toenails
Not every woman paints her nails, but for most who do it's another part of showing off that part of the body, so open shoes that reveal the painting contribute to that accentuation. I doubt any but the most extreme of fetishists are going to be admiring the choice of colour, the smoothness of her brush-stroking, the precision of her cutting-in, or the pristine sheen on her finish.
Many women consider their feet erogenous zones and objects of focus, so they wear shoes designed to make them look dainty, slim and shapely, hence the designs that so often cripple their toes.