The guide doesnt say it, the best place to get the Griffin swords/armor made (assuming you havent yet made it to Novigrad) is the blacksmith/armorer in Oxenfurt.

"From here if you follow the road south-east, the south until it bisects a road running north-east you’ll find the “Harpy Feeding Ground” signpost"

And if you follow it to the northeast you will find a sign for "Harpy Feeding Place

"Head along a road south-west from the camp until you reach a four-way split in the path."

In my version (next-gen update) there is no road leading southwest. But on the map on the site the road is presented.