I'm not intimately familiar with the camera to you have, but you could try to use a gel...which is just photographer-jargon for colored plastic in front of your flash.
It is used to adjust the color cast of a flash, but it can also be used to reduce the effective output of a flash.
You can buy gels in some photo stores, but I'd suggest that you might experiment with cutout from white plastic bags of varying thickness - or even try 2 layers for example. This can give you a very cheap indication of this route is worth pursuing.
Alternately you can try white paper of varying thickness.
In addition you might get the side benefit of diffusing your flash a little, thereby making the light less harsh.