I'm a full STR blader, and I'm taking both the Concentration series and the Vitsal Spot series in Force, since I'm levelling both trees anyway. I figure every little bit helps, and a blader with both will decrease the opponents hit ratio, dodge ability
and increase his own parry ratio. That means less damage x 2 for you + more damage to your opponent.
Add to that a good shield with crit reduce and you've got a nice tank.
(I know you're a nuker, I just wanted to add some info on my build)