"and this was last used by Pius XII and the dogma on the Virgin Mary."
That is an interesting point. It appears that Pope John Paul II, of blessed memory, pulled out the big guns on the issue of women's ordination. In the Apostolic Letter "Ordinatio Sacerdotalis" on 22 May, 1994, he wrote:
"Wherefore, in order that all doubt may be removed regarding a matter of great importance, a matter which pertains to the Church's divine constitution itself, in virtue of my ministry of confirming the brethren (cf. Lk 22:32) I declare that the Church has no authority whatsoever to confer priestly ordination on women and that this judgment is to be definitively held by all the Church's faithful."
(http://www.vatican.va/holy_father/john_paul_ii/apost_letters/documents/hf_jp-ii_apl_22051994_ordinatio-sacerdotalis_en.html It's not a long letter.)
The language he uses bears all the hallmarks of infallibility; it is actually quite similar to the language of Pius XII's Apostolic Constitution "Munificentissumus Deus," wherein he formalized as dogma the doctrine of the Assumption. However, I think there is a slight difference in the way infallibility was used. Pius XII settled the issue for once and all; previously most people had believed it, but the belief was not formalized. With John Paul II it seems that the issue at hand was more "re-settled." By this I mean that the Church had always, always taught that only men could be priests as a matter of fact; it seems that JPII wrote the Letter to re-emphasize the point to combat the happy-dappy liberal notion that all (women, non-Catholics, ham sandwiches, etc) have an intrinsic right to priestly ordination. So, it seems (to me) that your assertion that the last pope to use infall. to define a doctrine was Pius XII is true, with some qualifications.
The above are just my observations, and if I have misinterpreted anything, am incorrect, not precise, etc, please correct me.
Not that this has anything to do with the thread at hand, but I thought it was interesting....thanks for listening.