Questions about Specific AB Skills

How exactly does Power Transfer work? I get that it halves the damage that you take (which it mentions in the skill description), but it also mentions something about absorbing 1% of the damage. On OrangeMushroom, it mentions that it absorbs 1% for every attack you make up to 50%, but it doesn't seem to be doing that. I seem to get the 50% damage reduction right from the get go, and while the buff does seem to "refresh" itself every time I attack, it doesn't seem to be getting stronger. Also, occasionally, I'll not take damage from an attack and heal 1 HP (though it doesn't seem to heal me.) What's the chance of that happening, since it doesn't seem to say in the description.

Also, has anyone noticed that sometimes, you'll use a soul battery skill that has already been charged, and it just fails without actually firing. It's happened to me a few times, and I'm certain that I had the skill charged beforehand. It happens most often now with Celestial Roar and Trinity for me.