I did some testing in Peregrine Island, and I found the issue.
The good news: The damage bonus does take effect! The not so good news: The 2.5 second delay on the damage bonus doesn't start on activation, it starts on the hit itself. This results in a delay between the end of Arcanatime and the bonus kicking in. If you have your next power queued up right after Eagle's Claw, the bonus won't affect it!
Edit: If you're going EC->SK->CAK->SK, you still get that bonus on the CAK and second SK. So its more a matter of timing than losing the bonus.
Now that I've seen it in action, I vaguely remember something about this being an issue back in live?