1/3 of whatever is invested "into" whatever is invested, should be given back.
No matter if str/agi/skill points.
That flattens the pain for those who have specialised builds, which may not work now anymore. They can consider making different specialisations then, while the underlaying tendencies are kept.
Also: why not a full respec? It is clear that this is a major game change. From earlier changes and statements it was always clear, that at such a point a full respec would be viable.
Now also with my lvl 36 in mind, the higher in the level you get, the more time you have put into this grind festival, the more it hurts when changes are done and you couldnt simply adjust. Last time i saw an auction for Trainings Lessons, it was for 3 million gold wtf i roughly have 400k without any thing being bought in months(counting also back into the time i had been playing for longer then a month now). So either get us a fixed low price on trainings lessons to respec, or give us a full respec, but the bare minimum as i see it, 1/3 of everything we had spent skill or attr points no matter if agi or str.