The wording "Mediatrix of All Graces" is very confusing, and I have to admit that I found it confusing even when I was Roman Catholic. At the time, I took it to mean what my grandmother taught me it meant, which is that all the grace that God now gives to mankind on a daily basis comes through the Virgin Mary. It seems to me that it may be even intentionally confusing and intentionally vague so as to create an umbrella for unpopular beliefs, while falling back on valid beliefs as an explanation.
If Pope John Paul II held back on dogmatizing this for the sake of preventing further rifts between East and West, he was wise. To say "God became incarnate through the Virgin Mary" is perfectly Orthodox. To say "Salvation came to mankind by the incarnation of God through the Virgin Mary" is also perfectly Orthodox. To call the Theotokos "Mediatrix of All Graces" however, seems to imply that she is still the primary source through which God gives His grace to mankind, which is might cause most Orthodox to cringe. Even if that's not what is meant by it, it seems like a very bad term because of what it might imply.
We can all agree that she intercedes for us and perhaps even that her prayers are the most important of all the prayers of all the saints since the mother holds great sway with the Son. If the title indicates only her intercessory power, it seems strange, since all the saints do the same that she does through their prayers for us.
