Are you sure this is the way it should be?
I'm 100% sure the first weapon get enchanted at +10 the second one doesn't get enchanted it's stronger at +0 and you have to have Enhanced Shadow Ingot to get the third one which again doesn't get enchanted.
here from pts itemdata
first weapon ---> item_begin weapon 46317 [shadow_dagger_1]
enchant_enable=9 elemental_enable=1
secont weapon----> item_begin weapon 46327 [shadow_dagger_1_tr] bla bla bla
enchant_enable=0 elemental_enable=1 unequip_skill={} for_npc=0 item_equip_option={} use_condition={} equip_condition={}
third weapon---> item_begin weapon 47874 [shadow_dagger_1_tr_high] bla bla bla
enchant_enable=0 elemental_enable=1