NARCODIS'S PROFILE

You'll need an 'else' statement on a conditional branch that checks for the shield, and then inside each fork, make a conditional branch that checks for a switch, which I'll call 'SHIELD'.

In the first fork (the IF shield=equipped case), make a conditional branch to see if the switch is OFF, and if so, add 10 defense, and turn the shield switch ON.

In the second fork (the ELSE case), make a conditional branch to see if the switch is ON, and if so, subtract 10 defense, and turn the switch OFF.

IF (player has shield equipped) {
IF (switch SHIELD is OFF) {
Def +10
Switch SHIELD == ON
}
ELSE (player has shield equipped)
IF (switch SHIELD is ON) {
Def -10
Switch SHIELD == OFF
}
}

That should work, I think.
You also may want to make a conditional branch around the whole thing that checks to see if he has the passive skill in question, of course.

dear canuck:

you're gay if you think FFX had the best gameplay. there I said it.
though, I will say I think I like the battle system in X more than any other FF. the dungeons were just so laaaame.

ps. sorry for calling you gay.
pps. sorry if you are actually gay and i made an ignorant derogatory insult out of your sexual preference.

I'm going to hire Silviera to bug test every game I make ever.

This game is really fun. Really cool. Very well done.

at least finish befuddle quest. I imagine it wouldn't be that hard to piece it together.