What legs go well with heavy metal armor?

[Iscah]

It's a good question, and one that is probably going to vary with personal taste!

I don't like the look of the "plain pants under waist-length armour" either, so I've mostly been using skirts-with-pants-underneath for the legs slot. (Which you may or may not want for your male character, but it could look like you're wearing a tunic under your armour. Or it might be useful for someone else reading this.)

So for that approach, the options I'm aware of are:
Lv.1 Amatsu Haidate - if you did the FFXI crossover event a little while ago. A red "armour skirt" over black pants.
Lv15 Hall of the Novice gear - tanks can equip both the tank and DPS versions.
Lv15 Foestriker's Skirt from the first three dungeons.
Lv43 Boarskin Skirt - dyeable version of the novice tank skirt
Lv50 Storm Elite's Skirt (if you are in the Maelstrom GC) - costs 1000 allied seals though.
Lv55 Ramie Skirt (and)
Lv60 Chimerical Felt Skirt - both have the same model, but dye differently. The Ramie Skirt applies the dye colour to the pants and turns the skirt a darker colour, while the Felt Skirt does the opposite. Soot Black dye will turn the darker part jet-black.

Lv61 Ghost Barque Trousers of Fending - singling this one out because I think it looks really good with the Titanium Mail you mentioned. It's a chainmail skirt over black pants. It's a dungeon drop from the Sirensong Sea, but if you want to try it on, look up "Hemiskin Trousers" (there are a few DPS varieties) on the marketboard.



The other option (not counting longer skirts) is the Lv60 Hemiskin Brais of Fending, which has long drapes of cloth at the front and back, and black shorts underneath. If you try it on by itself it might look a bit odd, but once you combine it with the 'foot' armour, your legs are fully covered.

[Jandor]

Lv61 Ghost Barque Trousers of Fending - singling this one out because I think it looks really good with the Titanium Mail you mentioned. It's a chainmail skirt over black pants. It's a dungeon drop from the Sirensong Sea, but if you want to try it on, look up "Hemiskin Trousers" (there are a few DPS varieties) on the marketboard.

Going to second this one, the chainmail skirt is one of my go to glam options.

Looks good, works well with heavy armor, looks like you've got some padding underneath it.
Works well with lighter armor too, looks like you've got some actual armor on underneath.