Sentence:  And let such as will number the Kings of Castile and Portugall amongst the warlike and magnanimous conquerors, seeke for some other adherent then my selfe, forsomuch as twelve hundred leagues from their idle residence they have made themselves masters of both Indias, onely by the conduct and direction of their <WSD>factors</WSD>, of whom it would be knowne whether they durst but goe and enjoy them in person. 
Meaning of the word marked with <WSD> tags:  An agent or representative.