Should I shave my arms?

It sounds like your body type is similar to mine. Everyone is different of course, and shaving body hair or not is your individual choice. (Though plenty of people will have opinions about what you do or don't shave no matter what you end up deciding.) 

Personally, I shave my legs and armpits, but I have not shaved my arms more than a few times. Shaving my right arm with my left hand is awkward, and for some reason the hair on my arms just looks normal to me, but I hate my leg hairs. So again, whatever you choose. 

i have no idea .i never feel like itchy

You can, I shave mine, they don't itch. I've been shaving them for years. But the hair will grow back not as soft and smooth and relatively darker. So it's really up to you.

once you start shaving them you will have to keep it up

It's up to you. I feel like it's one of those you'll have to do on a daily basis if you can keep up. I used to as I used to be so self conscious, but I grew out of it. Mine didn't grow back thicker or darker either.

Give it a try. I am blonde with blonde hair, I started shaving mine a few years ago and never stopped. When they grow back they are pretty much as before, so you can just leave it if you don't wannt to carry on.

If you think your arm hair is longer/thicker than average, you may want to shave it.  If you think it's pretty fine and unnoticeable, I wouldn't bother.  I don't shave mine, and I honestly never notice any other ladies having unsightly hairiness on their arms, whether they're shaved or not.  ...Except one young woman whose arm hair was particularly dark and thick... nothing against her, but that's why I say that you may want to shave if you think yours is more noticeable than averag.