Reason why I wouldn't see ARN is because how close it reflects upon ARC. People made general confusions about Goldsmith and Gladiator that SE had to change the abbreviation for it, remember? It used to be GLA > Gladiator, GLD > Goldsmith. Players often confused equipment designed for Gladiators as something that could be used for Goldsmith. Now I know Archer doesn't have an "n" in the spelling but considering how close the abbreviations are to one another it's still bound to cause confusions. ARC, ARN. I might be wrong and they'll use it anyway, but I guarantee you there will no doubt be complaints or fusses because somebody bought a robe then realized it was for ARN, and not ARC.
Though, I suppose the same could happen anyway with ACN, still I feel that might have a lesser chance of confusion than having the last letter of two completely opposite disciplines being the only difference.
