Although containing minimal SCA terms (author is a member) this very well researched document thoroughly covers "Irish" and "Scottish" dress from 400CE - 1100CE.
Another Brigantia document. Covers, spears, swords, shields and other armour of Iron Age Britain. Much of this can be applied to Continental Iron Age Celts but not necessarily Irish Iron Age Celts.
The first part of this 2 part series covers the forging of a spear and discusses the differences between modern blacksmithing techniques employed and those of a period smith.