Stiletto of Demarchess does not grant an AC bonus.
Boots of Phasing is not a BG2 item.
Girdle of Glory is a mod item.
I know there is an Ioun Stone that grants +1 DEX, but I think the Helm of Balduran beats it flat.
Sword and Shield Style grants an AC bonus versus missiles, not to your base AC.
If the BMU is not considered magical, I would rather replace the Ring of Earth Control with the Ring of Protection +3, then wear an Amulet of Protection +1.
Effective AC is capped, but do not forget about penalties.
Whether it be by Slow or whatsuch. Hence my comments of, "~~ and good luck trying to 'penalise' it. ~~".