Sentence:  a woman of great authority, having first yeelded an accompt unto her Citizens, and shewed good reasons why she was resolved to end her life, earnestly entreated "Pompey" to be an <WSD>assistant</WSD> at her death, that so it might be esteemed more honourablenb.... 
Meaning of the word marked with <WSD> tags:  Someone who is present; a bystander, a witness.