GSF: Illusion bonuses, maybe?

[sankarul]

I was thinking... Other than for a wizard to take Spell School: Illusion, as someone just mentioned on discord, there are few reasons to even touch Illusion spell focuses. I really enjoyed Color Spray on my wizard earlier this year, but otherwise... it's really just PHK that gains from GSF. The small blur 20% concealment vs 10% is ... useful, but it's barely noticeable.

I'd suggest a few other conveniences. Maybe extended duration on Invis like Diviner gets on see invis? Extended duration on blur? I am unsure on the exact duration, but I think doubling the duration of these 2 spells would be a huge boost to the convenience of having GSF: Illusion, and might attract people into actually taking it.

What do you all think thonk?