Sentence:  [S]he loſt a noble and renowned brother, in his loue toward her, euer moſt kinde and naturall: with him the portion and <WSD>ſinew</WSD> of her fortune, her marriage dowry: with both, her combynate-husband, this well-ſeeming "Angelo". 
Meaning of the word marked with <WSD> tags:  That which gives strength or in which strength consists; a supporting factor or member; mainstay.