I looked at the rules and the powers again and I am still not sure if this can be done. Can you perplex your blades claw fangs damage? If I made a successfull attack and rolled a 4 on my bcf roll and had a clear line of site could I perplex the bcf roll of 4 to 5-7 depending on how many perplex pieces are on the team with line of site?

No. You perplex up the damage on your dial, and then replace that perplexed number with the dieroll.

Peers is right. Becuase you can't Perplex in the middle of an action. If you Perplexed BCF, you would have to in between the roll and resolution, becuase you roll the attack, see if it hits, then Roll BCF. Then resolve the damage. All one action, no chance to get Perplex in there.

I only just learned that BCF and EW work together.
Ouch.

Sorry for being slightly off-topic.

Thanks for clearing that up for me.