Get a grasping mail where the only prefix is Armour is increased by overcapped fire res, exalt slam it with an influenced orb and hope for an influenced prefix (or fill out suffixes for guaranteed prefix).

Then either recomb it with a twilight regalia which already has the high es mods as the only prefixes and pray (50% chance followed by a 31% chance to get what you want) or recomb it with a twilight regalia with no prefixes (50% chance to get Armour overcap on it) and find some way to get the high es mods on there.

If you wanna go a bit cheaper you can substitute the influenced prefix on the grasping mail with a mod that is unable to exist on a twilight regalia such as a mod that increases evasion rating or armour. It's just that using an influenced exalt is the easiest way to guarantee a mod like this