It can damage the hardware (in the long run) if you pass 18W power draw. But that of course is depending on the game you are playing. I would say, as long as you are not losing battery while playing you should be fine, if you do lose battery (even slowly), go down with the CPU/GPU clock.
wrong, only Erista can be considered dangeous, as it is already passing the 18W mark with 1785/921. Going over that will kill your console for sure.
Meanwhile a Mariko unit can do 2193/1305 without any issues, the console doesn't get considerely hot or draws more than 18W.