Curses have random effects on characters, they may be stunned and unable to attack, may lose some HP etc. On the other hand, you may be lucky and never notice such effects.

item	cost	equip on	location	effect
power ring	10,000 gold	anyone	battle #18	ATT+5, Attack 1
shield ring	10,000 gold	anyone	battle #12	DEF+5, Quick 1
quick ring	10,000 gold	anyone	battle #10	AGI+5
mobility ring	12,000 gold	anyone	battle #13	MOV+2
white ring	10,000 gold	HERO,BTLR,SMRI DGMN,GDVL,PRST	battle #20	DEF+10, Aura 2
black ring	8,500 gold	WIZD	battle #14	ATT+10, Blaze 2, cursed
evil ring	9,000 gold	PRST	battle #19	ATT+15, Spark 2, cursed