Hi.
About Portuguese Nobles (they had conection with many houses of Europe by marriage) there is this treaty with 17 volumes written around 1800 and reedited in the 40's that verses about noble families from Portugal, some since 1300's. Thiese books are online at National Digital Library of Portugal. Can you include in your section of "Non British European Royal Descent? It would help the work of others researching Portuguese nobles, as helped me (I would love to see more people into it). * GAIO, Felgueiras, 1750-1831
Nobiliário de famílias de Portugal / Felgueiras Gaio. - [Braga] : Agostinho de Azevedo Meirelles : Domingos de Araújo Affonso, 1938-1941 (Braga : : Pax). - 17 v. : il. ; 30 cm - http://purl.pt/12151/4/
And if I can improve to help more our wiktreers fellows on the subject, here are some other sources I consider fundamental to people that researches Portuguese nobles.
One treaty on Heraldics of most of noble families from Portugal, talks about how are their coat of arms and the origin of it.:
* Afonso Eduardo Martins Zuquete, 1987 (3ª Ed.), ARMORIAL LUSITANO - Genealogia e Heráldica, Editorial Enciclopédia, Lda. Lisboa. 1987 (3ª Edição), 733 p. : il. ; 26 cm
And two other books related to noble families genealogies of Portugal in the region of Madeira Island (land that is owned from Portugal):
* FRUTUOSO, Gaspar, 1522-1591 - Saudades da terra : livro II / Doutor Gaspar Frutuoso ; [Palavras prévias de João Bernardo de Oliveira Rodrigues] - Nova ed. - Ponta Delgada : Instituto Cultural de Ponta Delgada, 1998.
* Noronha, Henrique Henriques de, Nobiliário genealógico das familias que passaram a viver a esta Ilha d'a Madeira depois de seu descobrimento no ano de 1420, 1700, Revista Genealógica Brasileira, São Paulo, Brasil, 1948 (reprint), 3 volumes.
I hope this be useful.
Regards, Carlos.