IMO her W should be buffed and her Q nerfed. It's too easy to just poke down with Qs if your opponent is low ranged.
Make her Q scale 5 or 10 lower and her W scale 5 or 10 dmg higher per level invested in the skill.
Or... swap some of the first hit damage to the mark damage of her Q
Currently:
Dagger Magic damage: 60 / 85 / 110 / 135 / 160 (+ 45% AP)
Mark Magic damage: 15 / 30 / 45 / 60 / 75 (+ 15% AP)
Total Damage: 75 / 115 / 155 / 195 / 235 (+ 60% AP)
Change to
Dagger Magic damage: 40 / 60 / 80 / 100 / 120 (+ 30% AP)
Mark Magic damage: 40 / 60 / 80 / 100 / 120 (+ 30% AP)
Total Damage: 140 / 120 / 160 / 200 / 240 (+ 60% AP)