The actual check:

C2/5FFA: C9 66 CMP #$66         ;Compare accumulator to 66h (Cursed Shld value).
C2/5FFC: D0 0E BNE $600C        ;Branch past the rest if it's not the shield.
C2/5FFE: EE C0 3E INC $3EC0     ;Increment battle count (loaded from 7E:1DD5).
C2/6001: D0 09 BNE $600C        ;Branch past the rest if the battle count has not returned to 0.
C2/6003: A9 01 LDA #$01
C2/6005: 04 F0 TSB $F0          ;Tells the game to display "Dispelled..." text.
C2/6007: A9 67 LDA #$67
C2/6009: 9D 1F 16 STA $161F,X   ;Stores the Paladin Shld in equipment spot.

The way the check goes is that you can uncurse it in any slot.  Interesting.  As for Gogo,
I may try to find out why he can't uncurse it later, but don't hold me to it.

Other notes of interest:

$C2/2435: A2 13 LDX #$13
$C2/2437: BD C9 1D LDA $1DC9,X
$C2/243A: 9D B4 3E STA $3EB4,X
$C2/243D: CA DEX
$C2/243E: 10 F7 BPL $F7 [$2437]

$C2/49D5: A2 13 LDX #$13
$C2/49D7: BD B4 3E LDA $3EB4,X
$C2/49DA: 9D C9 1D STA $1DC9,X
$C2/49DD: CA DEX
$C2/49DE: 10 F7 BPL $F7 [$49D7]

Besides 7E:1DD5, I have no idea what's in these offsets or why they're moved.