I think, that there may be few different reasons for such blur.
In some cases it may be controlled by OS, but most probably it's not our case.
It may be somehow corellated with textue sampler interpolation technique, that samples pixels at the center of pixel (at 0.5x, 0.5y coord, for example), so that UV coords passed to sampler must take it into account.
Most probably, as far as i see, it's result of how fonts managed in Kha. When you load new font, tool, named Kravur creates font texture. And then during render process function getBakedQuad() takes small quad for each rendered character. It's part of optimization for render process. Therefore we have multiple points, where font can be resized and resampled.
Please, note, that i'm not very familiar with Kha, so my statements may be completely wrong.
One possible solution, that I see, to achieve pixel-perfect fonts - is to bake your font into texture, for example with this online tool: http://kvazars.com/littera/
And then adopt graphics2 internals to use your texture, instead of loading from *.ttf