1. I fell upon a Google book:

Archaeologia cambrensis by Cambrian Archaeological Association

Under the Its Conquest and its conquerors chapter, Page 19 it states:

St. Armand was the patron saint of Thorigny, sometimes called
St. Amand de Thorigny.

• What is Thorigny?

Thorigny-sur-Marne is a French commune located in the Seine-et-Marne département, in the Île-de-France région in France, near Paris.

Inhabitants of Thorigny-sur-Marne are called Thorigniens.

Here is a Google map of the place; it looks about 15 miles north of Paris.

So it appears that this saint may have been well known for addressing the pastoral, spiritual and physical needs of the people of Thorigny-sur-Marne.

2. Wikipedia also had this entry, where it stated it could be several people.
   
   Under Saint Amand, they said:
   
   
   The 7th-century Saint Amand has given his name to numerous places named Saint-Amand, (as well as variations Saint-Amans and Saint-Amant)
   
   
   With this in mind, I found the founding entry in my Pocket Dictionary of Saints by John J. Delaney for St. Amand:
   
   

   St. Amand (also Amandus)— (c. 584 A.D. — c. 679 A.D.) Born at Nantes, Lower Poitou, France he became a monk around 604 at a monastery on the island of Yeu, was ordained at Tours, then lived as a hermit for fifteen years at  Bourges. On his return from a pilgrimage to Rome, he was consecrated a missionary bishop in 629, with no sea, and devoted himself to missionary activities in Flanders, Carinthia, and probably Germany. He was banished for censuring King Dagobert I, was recalled, then despite initial difficulties, was highly successful in evangelizing the area around Ghent.  He founded numerous monasteries in Belgium, may have been chosen bishop of Maestricht, but after three years resigned to return to missionary work. He spent the last years of his life an abbot of Elnon where he died February 6.

   Another article said:
   
   

   As well as being a great missionary, St. Amand was a father of monasticism in ancient Belgium, and a score of monasteries claimed him as founder. He found houses at Elnon(e) (Saint-Amand-les-Eaux), near Tournai, which became his headquarters, St. Peters on Mont-Blendin at Ghent. It is said, though possibly apocryphal, that in 646 he was chosen bishop of Maestricht, but that three years later, he resigned that See to St. Remaclus and returned to the missions which he had always had most at heart. He continued his labors among the heathens until a great age, when, broken with infirmities, he retired to Elnon. There he governed as Abbot for four years, spending his time in preparing for the death which came to him at last soon after 676.

   That St. Amand was one of the most imposing figures of the Merovingian epoch, is disputed by no serious historian; he was not unknown in England, and the pre-Reformation chapel of the Eyston family at east Hendred in Birkshire is dedicated in his honor.