Ok. So how about Silphio tried to use projectile weapons and realised he was really terrible at them. He somehow tends to hit the thing directly behind him instead of what he's aiming (unless he's aiming directly behind him, he'll usually hit himself then).
Nerfwise how about he's unfamiliar with his allomatic bronze, he can only recognise the rhythms of roshar and use of true flight, which only he has.
And for the counter Kara-Kara is especially sulky, if Silphio forgets to feed her or ignores her she'll take some of Silph's investiture, depending on how sulky she is, she can almost halve Silph's armour strength, flight speed and manoeuvrability.
Sound good? @Archer