It wasn't an angel pose, it was simply covering their face in a pose of 'shame'. The angels use that to cover their eyes from each other, I think.
To Quote another poster,
Did the TimeLords get this from the Angels or did the Angels continue the TimeLord tradition?
The Time Lords got it from the Angels. To quote Rassilon:
"The vote is taken, only two stand against. As testament to their shame, they shall stand with us like the Weeping Angels of old. And now the vanguard stands prepared, the children of Gallifrey are ready to rejoin the universe. To Earth!"