Let's face it, this (light attack weaving) is a silly mechanic that should not be in the game. There's no reason why a light attack should be required with every single ability to maximize your output. Not only that, it really isn't fun. It's not difficult. It does not add to the game. It rather breaks immersion, for those who like a little more realism.
So, here's my suggested fix: Make light/heavy attacks and abilities equal priority, with neither interrupting the other.
This means players can still stop what they are doing, but they have to block or bash to do so, which allows for defensive actions without forcing light attacks as part of every ability... and making there be a moment of no attack which will break the usefulness of this technique.
I know there will probably be some people against this as it would be a 'loss of dps'... but honestly it isn't fun gameplay, and even if it stays the difficulty must be balanced against it (Thus, the loss of dps argument is a straw man, because without it in the game you won't need as much dps.)
Constructive suggestions more than welcome!