I have a question about the new vestigial arm description. It's says the arm by itself doesn't grant newattacks but can be used as part of your two weaponfighting routine. so if I'm quad wielding axes doiI get 3 extra attacks or stuck with just the one?
You get a single offhand attack due to the axes in your original two arms; the extra weapons in your vestigial arms grant, as it says, no extra attacks.
A litmus test I've seen advocated that holds quite well is to ask "Could I get this many attacks with just two arms?"