What does the term sinewy most closely mean?

4. at the conclusion of frankenstein, robert walton has an encounter with the monster, who arrives after victor frankenstein has died. perhaps surprisingly, the monster mourns his creator and expresses remorse over the fate that victor suffered. the monster pledges to destroy himself and then departs, disappearing as he goes further north. how does the monster’s behavior and attitude in this part of the novel affect the way readers view him? is he sympathetic? is he more hateful because it is only after victor has died that he relents? how does the change in the monster fit with the theme of duality in the novel?