Spear Dancing Style + Bladed Brush question

[Diachronos]

I'm considering building a Dex-based Fighter who takes advantage of Bladed Brush Combat, Slashing Grace, and Spear Dancing Style all at once, but I'm not entirely sure how they'd interact together.

On one hand, Spear Dancing Style says that you treat the polearm/spear weapon in question as a double weapon, meaning that it would involve two-weapon fighting and thus negate the "can't have anything in your off-hand" clause of Slashing Grace.

On the other hand:

Bladed Brush Combat wrote:

When wielding a glaive, you can treat it as a one-handed piercing or slashing melee weapon and as if you were not making attacks with your off-hand for all feats and class abilities that require such a weapon

Does Bladed Brush Combat overcome the fact that using a double weapon wouldn't allow you to use abilities that require a free off-hand? Or would Spear Dancing Style negate the benefits of using Slashing Grace? In either case, I'm assuming that the "light mace" part of the glaive wouldn't benefit from Slashing Grace despite technically being part of a weapon being modified by the feat.

Apologies if this has already been answered; I searched but didn't spot any threads that looked like they answered this particular question.

[Nefreet]

Nobody knows how Bladed Brush works. It has spurned numerous threads and was likely banned from PFS due to its ambiguity.

I would suggest asking your GM how they would rule it.

[dragonhunterq]

Oh, we all know how it works, I think its more accurate to say no one agrees how it works :)

[Wolin]

Based off quarterstaff master, likely you wouldn't be able to use a glaive held in one hand as a double weapon. Both cases you're holding a double weapon in one hand.

Sounds cool though! Cool enough that your GM might let you do it anyway if you ask.