DracoSuave
First Post
And yet you didn't answer the question: where is this described? Why does +4 vs. daze&stun work vs. daze&weaken?
Because "daze and weaken" is a dazing effect.
The feat does not say '+4 to save against daze (save ends)' but is far more open ended. It simply requires it be a dazing effect, and thus, 'dazed and weakened (save ends)' qualifies.
To take it even further, a dwarf can apply his saving throw against poison... that doesn't even mean 'ongoing poison damage' but any poison effect that requires a saving throw.
So, if there was a power with the Poison keyword that gave 'dazed (save ends)' like, as an explicit example Prismatic Beams [wizard attack 15, phb], then a dwarf with that feat would get +9 to their saving throw against the non-damaging Will-defense effect of that power.