As we saw, Pycelle had a public act of stooping over, mumbling and seeming 'older'. He straightened up in private and was more literate.
So when he was being murdered, why did he continue the stooping, dithery old fool act?
The only time we saw him stop doddering was just after he'd screwed Ros.
The effects seem to have been temporary.
He swung at the kids though with his stick...
shareHe was trying to swing at them and fight them off, there were just to many of them, and they were stabbing him.
He also stood up straight and spoken more coherently when Tywin told him that he knew it was all an act.
In season 3 0r 4 DVD, there is a deleted scene in which Tywin is talking to Pycelle. Tywin is fishing and Pycelle and he is pleading to Tywin for his old job back at the council. Tywin isn't that receptive to the request; he also tells him to give up the old man act - which he does very briefly.
It was all an act but I suspect when he was being murdered, he was actually dying.
It was a nice addition that hinted at him not being all that he seemed.
It was also an addition that went absolutely nowhere in the scheme of things.