Attack/Defence/Movement should be proportionally balanced between thief and archer.
Righ now thief has clearly higher defence and movement and a bit advantage in attack (range, can use distant rare)..... and invis.
So i would recomend to increase archer damage in proportion that thief has movp/defend advantage.
For example, thief has ice defence skill that stacks with main attack skill.
Give archer similar +damage skill, and remove possibility to get pro/sfd after charge.
Or just increase archer base damage.
Just giving archer ice blast like skill only balances the small difference in attack.. and thief will still have movp/defence.
Keeping the topic alive.. would be nice to see more archers.