There is literally no relation between Windwalker monks and the Fist of Ra-den except for:
1.Ra-den appeared during the MoP Expansion
2.Fist weapons are iconic to Windwalker
The Lore of the Fist of Ra-den has absolutely no relation to Windwalker Monks.
Elemental works for the WW Fist weapon(s), but WW doesn't work for the Elemental artifact.