Arcteryx has traditionally been a brand specifically for climbers who are generally lean and wiry (athletic build). I bought a jacket years ago (it is my favorite jacket). It was a men's small, which obviously some guy bought at REI and found it too small so it ended up on the sale rack. I am a 5'4" and thin woman and it fit me perfectly. My problem with women's sizing is that my shoulders are too wide and arms more "athletic" than most women of my size, so the men's x-small or small work better for me. The sleeves are a bit too long, but that is not a serious problem. I sew, so I just hem them up a little.

Rock climbers particularly do not like a lot of bulk (prefer tighter fitting stretchy clothing), so their layering usually consists of a thin base layer only.

You need to size-up in many brands of climbing clothing if you intend to do more than the thinnest layering.