Is there a cap on how low weapon delay can get via haste?

[Safon]

And if so, what is the lowest weapon delay can be reduced to?

[Slave]

6 I believe.

[Lazortag]

I think it's 5; just search for bug threads on the Mosscovered Twig and you'll find your answer (since it was lowered due to complaints about the Twig not being classically powerful enough. Also you can probably search for patch notes)