Color wise, you could get black, blue and/or silver from the blue hen, and black and/or blue from the black hens.
Body type, they should be more slender and upright than the Swedish, but not as slim or upright as the runners.
If it was the other way around (fawn/white runner drake and pekin hen), the hen ducklings would be brown+blue (lavender) and the male ducklings would be blue, at hatch. Sexable as day Olds. :)
In the US, fawn and white runners have blue genes. Specifically, they are dark phase dusky with sex link brown and homozygous blue. So that's likely where the blue came from. If you bred one of these boys back to his mum or other fawn and white runners, you could get all sorts of very...