Axes tend to combine high power with physical bulk, and have several very well regarded units. Some of them even come ready equipped with Distant Counter. Unfortunately, I don’t actually own most of them, so have a very limited selection of Axe units (outside those which fall into the non-infantry categories).
Probably my luckiest set of rolls result in 2 Brave Ike during his original banner, who I quickly merged. He comes with very good default skills, so needs very little effort to turn into a powerhouse. He was designed to counter the Brave weapon meta, by weakening consecutive attacks, and quickly charging Aether. He is a core member of my infantry team, and regularly finds use in Grand Hero Battles and Arena Assault.
Since his basic skills are so good, and changes are so high investment, all I’ve done is add Reposition. This is unlikely to change unless I’m suddenly overflowing with inheritance fodder.
My only other notable Axe unit is Anna, who like Alfonse was promoted to 5* so I’d always have a bonus unit in Arena. She’s basically just a fast Axe unit, with not much else of note.
I kept all her default skills, but added on Darting Blow, to make her double even more units, and Reposition, because it’s good.
Of my remaining Axe units, the only ones worth mentioning in passing are a 5* Raven, and a 4* Legion. I’ve not put any effort into them beyond getting to level 40, but they sometimes come out in Arena Assault. Until I roll some new units, not much is likely to change here.