It seems that the attribute point GUI is bugged. At the time of writing this, I'm currently a level 25 shadowblade with all attributes maxed out. I did this by subtracting 1 attribute point from any attribute, and it returned tons of attribute points to be added later. I don't know what the precise amount was for each subtraction because it seemed to vary depending on how much points you already had in that current attribute.
It seems I was able to go higher than 64 attributes because, as I kept adding to the existing maxed out attribute over and over, it wouldn't go below 64 when I tried to subtract it.
Also, although my attributes are maxed out, they don't accumulate to your total attributes anyway. It seems I'm still at the default T2 shadowblade attributes:
It seems I was able to go higher than 64 attributes because, as I kept adding to the existing maxed out attribute over and over, it wouldn't go below 64 when I tried to subtract it.
Also, although my attributes are maxed out, they don't accumulate to your total attributes anyway. It seems I'm still at the default T2 shadowblade attributes: