Refine Teories !

Story:
When i was refining my Toy Sword in
.
Sofya:
+8 fail +8 fail +8 fail +7 fail +7 success +8 fail +8 fail +8 fail +8 fail +8 fail (...)
.
Fort Bailune:
+8 fail +6 fail +5 success +6 fail +5 fail +4 (...)
.
Maios:
+7 fail +5 success +6 fail +4 (...)
.
Back to Sofya:
+6 success +7 success +8 fail +7 fail +7 success +8 fail +8 fail +8 fail +8 fail +8 fail (...) success +9
.
.
.
From what i experience we can see
1. sofya got better success rate,
2. downgrade rate is lower too
.
.
.
my teory is:
1. npc blacksmith have different success rate with different weapon
example: toy sword = sofya blacksmith
.
2. each day at random some npc have better success rate, so don't stay at one blacksmith npc when feeling refine struggle.
.
Note: don't ask why i refine Toy Sword