The halloween spheres and lexida are actually stronger than amanohabaken I think - even in terms of pure damage if you are using a damage up leader it compares pretty well.
Assuming a leader like Dia or Lodin Amanohabaken iwould be 225% hits for your normal hit ( 100% + 50% for Dia + 75% for amano ) at 30% chance of 150% crit, or 326% damage.
The weak halloween sphere is 50% for the extra hits so you get 150% hits for the normal hit and 100% for the second hit, at a 10% chance to crit for 150%, or 287.5% damage.
The strong one is 75% for extra hits, so 316%
Lexida is 100% for extra hits, so 345%