Agreed, K/Wl is quite lacking atm. I suggest 50 focus restoration, like Warlock's Heart Collection Strike. Moreover, I'm still in favor of changing it's damage calculation to the usual % mainhand weapon dps (and reducing the numbers accordingly).
I doubt this alone will make the class viable again, but definitely would be a nice change.
I think GCD and focus would be enough for now. Perhaps it coud give some less focus but the cooldown would also be lower, then the damage would also be fine as it is. Don't wanna overbuff the class, otherwise it may turn out to be the next R/Sc xD
K/Wl is currently the worst chain class, well, maybe with the exception of D/W (although Druid at least has a battlerezz & other meaningful support). Imho there is no reason at all to play it. If you want a tanky offtank-dps hybrid, K/Wd does the job much better. So I don't see this change being sufficient or the class being at risk of becoming op.
K/Wl has the worst sustained dps I've seen so far from across all classes and not enough burst to make up for it. Borderline useless in my experience, while no cds are up.