So today I was wondering whether I should equip my Kokoroon's Darkshell Mail or my vintage hauby.

Im a lancer with a Bannerret Lance+1. Without any chest armor I have:

180 attack, 146 acc.

With kokoroon's Darkshell Mail I have:

185 attack, 151 acc

With vintage hauby I have:

180 attack, 146 acc.

So whats the point of the Vintage hauby +stats if they dont affect me at all? whats the point of it having a nice +8str +4 dex? Also..why do I have less hp when equipping a vintage hauby (its only 20- hp but it bugs me as to why its being deducted).