VIA JP thread:
http://forum.square-enix.com/ffxi/threads/1026/page2

Attachment of fire attribute
Strobe: +emnity (+5/+10/+15/+20)
T. spring: Attack (+3%/+6%/+9%/+12%)
Inhibitor: Store TP (+5/+10/+15/+20)
T. spring II: Attack (+6%/+9%/+12%/+15%)

Attachment of ice attribute
Mana booster: reduce cast time by (s) (- 2/-4/-6/-8)
Loudspeaker: +MAB (+5/+10/+15/+20)
Loudspeaker II: +MAB (+10/+15/+20/+25)
Tranquilizer: +MACC (+10/+30/+40/+50)
Power cooler: Consumption MP (- 10%/-20%/-35%/-50%)

Attachment of wind attribute
Accelerator: Evasion (+5/+10/+15/+20)
Scope: Range ACC (+10/+20/+30/+40)
Accelerator II: Evasion (+10/+15/+20/+25)
Turbocharger: Haste (+5/+15/+20/+25)
Barrage turbine: # of arrows you shoot, (0/+2/+3/+4)

Attachment of earth attribute
Armor plate: DEF (+10%/+15%/+20%/+25%)
Armor plate II: DEF (+20%/+25%/+30%/+35%)

Attachment of thunder attribute
Stabilizer: ACC (+5/+10/+15/+20)
Stabilizer II: ACC (+10/+15/+20/+25)
Dynamo: Critical hit rate (+3%/+5%/+7%/+9%)
Coiler: Double attack (+3%/+10%/+20%/+30%)
galvanizer: Counter (+10/+20/+35/+50)

Attachment of water attribute
Mana Jammer: MDB(+10/+20/+30/+40)
Stealth screen: Emnity(- 10/-20/-30/-40)
Mana Jammer II: MDB (+20/+30/+40/+50)


Most was already known, but nice to have clear definitions finally. Now if only they would list that for ALL attachments...and for english players as well. Instead of you know, going on and on about comet / meteor.