Armor found in Vagrant Story fall into one of four categories. There is no word in the English language for "piece of armor at a particular location on the body", so for the sake of this guide, the awkward but functional word 'Equipment' is used, as in, "A Cabasset and a Dread Helm are both equipped on the Head Body Location, and are therefore both Equipments of the Helm type".
The levels of armor, from weak to strong, are called Tiers for the purpose of this guide. Armor Tiers, and therefore the individual pieces of armor within this Equipment category are arranged by Defense (STR), from weakest to strongest.
Note that while the values for Strength, Intelligence, and Agility are true for any Equipment by that name, the Type resistance values (Blunt, Edged, and Piercing) will be altered by crafting, and can all three be raised as high as 100 for any Equipment.
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Jazeraint Helm and Dread Helm resistance values for weapon Type may well be available in the game code, but they do not drop in game, nor are they found in chests. So, ingame, those values will always be a product of the ingredients used in crafting them.
Helm Combining Edit
The progression of Helm combinations is broken at Sallet; no combination of helms below Barbut makes a Barbut. This both disables and inspires crafting, as Sallets are notably weak in weapon Type resistances, and many combinations can produce a Sallet of good quality from the tougher leggings and body armor.
Mismatch is a tendency in weapon combination, but a rule with armor; there is a direct correlation between how far away the Tiers of combined pieces are and how high the Tier of the result is, but not the correlation one might expect, namely that the closer they are, the higher the Tier. In fact, it is the opposite; there is a heavier penalty on combinations that are close together but not consecutive, than there is for combining a very low armor piece with a high one. It can be seen when the highest Tier helmet, the Dread Helm, is combined with other helms; the higher the Tier of the helm combined with it, the lower the Tier of the results.
Note also that Jazeraint Helm is more effective at protecting against magic than Dread Helm. It is also more effective at physical protection, but spells are arguably more dangerous (Banish, Area Effect damage) than physical attacks. There are no additional benefits from armor Strength other than physical protection. And there are no additional benefits from Dread armor other than armor Strength. This is also true of comparisons between other Jazeraint Equipments when compared with their Dread counterparts.
All of the same strategies for combining armor can be used to make Jazeraint instead of Dread; simply double the numbers of the pieces that go into the Hoplite, so there are 2 Hoplite pieces to make 1 Jazeraint piece instead of 4 Hoplite to make 2 Jazeraint.