It's not an issue of taking down a troll it's numerous other issues. Wtf are 9 elves who had trouble with a troll going to do if they find Sauron. You also have the absolute stupidity of the springboard sword. There is a difference between taking down an enemy and taking them down in that way.
Like if those elves couldn't take down a single troll with 9 of them without her going super hero mode they are just going to instant die to Sauron.