For a new player, one of every element would be a good starting point. From then on you can branch out to different builds if your party has an alternate source of DATA.
By the time anyone manages to grind 2-3 daggers they'll have other options for elements they didn't prioritize and won't need to grind the other daggers. I didn't feel the need to elaborate on such an obvious point.
I also think that shoehorning yourself into playing dagger classes is pretty bad on how you learn to play endgame. Not every build needs to have massive DATA.
Can you link me the site that lets you do these graphs?
>http://hsimyu.net/motocal/