Drop rate for green items is very low to start with, if you bring henchies or a full party, you'll have to consider that the chance of the item dropping for you will be lower since it could drop for anyone. If you can solo the boss, I'd advise doing so, otherwise if you can guildies are often the best solution or as few henchies as possible. If the stats for the sword are the only thing that interest you, check the list of
green weapons on guildwiki to see if there's a replacement green sword with the same stats that could be easier to get.