What is the participial phrase in the following sentence?

noted for her beauty, helen of troy was to become a well-known character in greek mythology

The participial phrase in the given sentence is "noted for her beauty". A participial is a word that ends in -ing form (present participle) or in -en (past participle) form that functions as an adjective. A participial phrase consists of the participial and other words that modifies or complements the noun. The participial phrase "noted for her beauty" describes the noun "Helen of Troy".