I think I am supposed to post here >.> .Well choose a Sadida not an Eca and go full str.But if you insist on Eca, go str untill 100 then vit 50 then str to 150 and when you are at total 150 str & 100 vit you can either choose go full str or 200 str/ 200 vit (and after that kep pumping str ).
By the way crit hits play a leading role in the Eca class.I can say more than every other class cause even their buffs have crit hit.
For example Wheel of Fortune actually adds +100 to str /int / chance/ agi when used and if it crit hits +200 so if yo umanage to have WoF 1/2 crit hit rate (yo ualready have all other spells and weapons to 1/2 too cause WoF is 1/50 normally ^^) you can be quite deadly. And if you decide to search it a bit more , you can combine that with rekop lvl 5 and some nice scrolling to chance/agi(+reflex)/int and then you have 1 hit-kill spell.
And with some good +dmg equip rekop becomes even deadlier.
If yo uwanna know more ask.