Wouldn't it be more effective if the blades were facing the opposite direction?

your right with 1 blade facing back its a more effective attacker but that would also raise the chances of it cutting the wielder its the same with any duel ended weapon

Why'd it be easier for attack? You could only take hits at opponent from one direction while this design could, when blocked, be used to slice opponents balls :D (or feet). Blocked from fight, take a new swing at opponent from left.

As long as you have steel gauntlets or chain gloves that would also be pretty good for defending.

yes but with one blade reversed and strong force applied it could be spun at an angle for successive devastating hits

Please see below! (^w^)

Yes, and the reversed blade's blunt side would also be useful for blocking and parrying.

but its at the other end of the pole meaning you speed would have to be greater than your enemy's in order to block in time i guess the greatest advantage of this weapon is that the center pole itself could be used to block.

Using the blade would be better in most situations because the force of the swing would divert the force of the attack away from you. Blocking isn't just about stopping, it's about diverting. Rather than try to absorb the force of the attack, it's more efficient to divert the force away. Basic physics supports this as a component of the force is applied on you rather than the full magnitude.

Also, your illustration depicts the handle having the same length as the blades. So not only would the difference in speed be negligible, but also the blocking surface area would actually be larger if you use the blade.

Please see below! (^w^)

first its not my illustration

also taking the force of the attack can be a good tactic as stopping the attack with the shaft can be used to open your enemys for a deadly strike and i've learned that negligible speed differences can be all it takes to decide a battle between to skilled warriors.

O.o I think this post is having good feedback!
I'll try to answer everyone in this reply.

Hyakujunoou is more like a medium reach defensive weapon, the blades are intentional, as it can strikes both sides of the wearer without much effort.
It IS capable of successive hits, but demands great ability and speed, intercalating thrust and swings.
The same way it can defend-counter with easy in the same swing, using the blunt back to draw the enemy outside and the other blade can strike.
Good idea to use the shaft too! And it can be used to push away enemy that are too close to strike.

I don't know if you all would agree with me, but, to tell the truth, I've saw weapons much more unbalanced and extravagant in many animes, and it's wearers handled it like a piece of (very powerful) stick! XD

Thank you all for the comments! Please continue to give me feedback like these, they're important for improving! (^w^)

Haha You can also see people fight with a sword in their mouth in anime :D (I couldn't keep on watching One Piece. Its too fucked up :P ).

I got somewhat interested now and drew what sort of toy I'd like If I had to have something similar to that.
http://img684.imageshack.us/img684/9302/tempaa.jpg

It seems cool! The blades are different from each other, then I could say one is for main attack? How about the fighting style? (^w^)