Strike n Smash 
Phys. Attack Power:  13-18 (150%)
Soul Cut Blade
Phys. Attack Power:  31-37 (120%)
By the numbers, it would seem Soul Cut Blade should do more damage.  I've tested the two skills extensively and Strike n Smash does more damage.   
 
 
Does anyone know why that's the cause? Test it out for yourselves.. you'll see what I mean.  Also, what does the 150% and 120% mean?  It can't be cooldown time because Illusion Chain (67%) takes longer to cool down than Soul Cut (120%), but Soul Cut is also faster than Strike n Smash (150%).