'stemnetton' - Harris (1976) suggests that this may mean 'they stopped talking' as opposed to the usual translation of 'stood fast'. He notes that it is unique in Old English and that in the context of the poem either translation is possible. Etymological evidence provides us with no clues alas, but he does point to a single occurrence in Middle English (in the Life of St Katherine) where it does appear to mean 'to keep quiet'. It is up to you as to whether you accept Harris's suggestion but it is another interesting example of how one decides on the meaning of words, especially in Old English where it is uncertain how representative is what survives. That is to say we can look at other occurrences in Old English (if there are any, check the Old English Corpus) to see if a clear meaning emerges, look at comparative languages and literatures, look at other possible etymological routes, and finally see if forms of the word survive into later periods.