I honestly don't remember a lot of people opting to play single classed low level M-Us, and when they did they never seemed to last long enough to matter. To say that they were squishy is an understatement. Most M-U's I remember either multi-classed or if they had the attributes for it made an early class swap after starting out as a fighter to get a hit point boost, or more than likely were made as characters when the player was allowed to introduce a higher level character to the campaign either because they were new or the DM didn't want to make them start over at 1st.
In any event, dart is the way to go. While I can see an argument in favor of the versatility of the dagger, the dart storm is clearly the way to go at low level. The dart's superior rate of fire, superior range, lighter weight, and lower cost made them much more practical than a dagger storm. You had to assume that if you were taking hits in melee you were going to die, and you wanted a weapon you could hurl without worrying about whether you needed to recover them all. A quiver filled with darts gave you some reliable damage.
I'd also favor staff over dagger. If you are going to get stuck in melee, at least have a weapon capable of killing most of your foes and which you might talk the DM into letting you use from the back rank, and which you might get a first attack with should a goblin with a club or short sword charge you. Dagger seems like a compromise, but as an M-U you really can't afford to be compromising. You need an absolute advantage, or you basically have none.