What else are you equipping on the hand slot? Also are you using anything like an arm harness? I can't remember specifically its name, but it prevents using gloves as it covers that part but I think the partial ones does, if you understand. The layering system is a pain in the arse especially with all the new armour types added with the various mods, I spent a good 2 hours theory crafting finding out which ones are best, I do setup my military with two plate gauntlets as they tend to sometimes only like to equip 1, same with plate boots, perhaps this is whats happening.
People can correct my build if they know better.
Helm Metal
Hood x2 Padded
Plate Armour Metal
Mail shirt x3 Metal
Cloak x6 Padded
Greave Metal
Trousers x2 Padded
Plate gauntlets x2 Metal (Sometimes they only equip one)
Mittens x2 Padded
Plate Boots x2 Metal
Shoes x2 Padded
Tower shield wood early on then mithril (very light metal) or if very strong and high armour user skill then a heavy metal type for more bashing damage
Generally I go for axes (Bardiche if I can, it's two handed normally, or 1 handed depending on strength/size of dwarf. It has massive contact area and most of the time if it hits it usually severs) best vs most IMO, its far too circumstantial to say 1 type of weapon is best though, e.g. spear for megabeasts titans, whips/warhammer for armoured etc
I can't remember about great helm / horned great helm being better I got frustrated at that point after spending so long on reading into the stats same with arm / leg harnesses.