I buy a lot of vintage.  One of my latest purchases is a lovely red aran cardi.  I couldn't resist -- the bargain-basement price was a factor, but I loved it most of all because it was red.  You never see red arans.
But damn it, it's itchy.  Wow.  I can see why it ended up lonely and forlorn in a vintage store on the clearance rack.
But wool is hair.  And conditioner is good for hair.  So there's no reason why conditioner isn't good for wool, I figured.
I'd read about using hair conditioner to soften itchy sweaters.  And it works!  A good old simple cream conditioner, and I soaked the sweater for over an hour -- but it is noticeably softer.
Very pleased.