Ash will split very easy just take yor time.
I use two axes and two wedges usually. I never hit my axes with anything other than a lump of wood.
You can make a wooden mallet with a hand saw and an axe in a few minutes. Same with wedges.
Metal on metal is never a good idea, at best will ruin your tools at worse ruin you.
Wish I could find it but used to have a great pic of a guy who split a 3ft log with only a tiny pocket hatchet and wooden wedges he carved.
Edit, my axes are GB hatchet and a GB scandi forest axe. You wont hurt your axe unless you start bashing it we metal