W9 quickness question

[bbz]

I have been testing quite a few times now the quickness from water 9 bless but I cannot figure out one thing. It is said to give blessed units + 50% action points and another attack every other turn. Does that quickness stack with boots of quicknes in terms of how many attacks a unit can make a turn(I know that it doesnt give extra action points beyond the doubled one from boots).
so if we have a normal unit(blessable) that normally does 2 attack a turn, with quickening(or boots of quicknes) he can attack 4 times
would that unit be able to make 5 attacks a turn(basically getting 2 extra attacks every other turn) if it is blessed?

Thanks in advance for the responce.