"his privy parts": This tells me only of his privy parts. Whence do I derive (the same for her seizing) anything which places his life in danger? From "and she seize" — in any event.
(Devarim 25:12) "Then you shall cut off her hand": We are hereby taught that you are obligated to rescue him (from her). Whence is it derived that if you are not able to rescue him by (cutting off) her hand, you must rescue him by her soul (i.e., by killing her)? From "you shall have no pity."