Barring the Gates to Foundation
Location
Required Items
Rewards
What the allowance actually buys
One allowance here buys 456,810 EXP, the best of the 3 Lv 50 Blacksmith tradecraft leves that record EXP: the runner-up manages 395,450 EXP, 13% less.
Across that rung the return runs from 70,850 EXP to 456,810 EXP per allowance — 3 distinct figures spanning 545%, so the wrong pick leaves 385,960 EXP of the allowance unspent.
On whether to wait: the best Lv 52 Blacksmith tradecraft leve returns 629,850 EXP per allowance, 38% more than the best on this rung, while the Lv 45 rung behind tops out at 137,400 EXP.
At Lv 50 this data holds 54 leves paying EXP across 3 categories: the 24 Tradecraft ones average 238,216 EXP per allowance, the 3 Fieldcraft ones 834,862 EXP and the 27 Grand Company ones 132,961 EXP, which puts this leve 92% above its own category's average.
Mythrite Katzbalger ×1 is a Lv 51 Blacksmith recipe, 2 steps deep through 5 intermediates, costing 32 units of raw material and 26 crystals.
Handing that in returns 14,275 EXP and 21 gil for every unit of raw material the order swallows, and the tree needs Alchemist, Blacksmith, Carpenter and Leatherworker.