PW's advice spot on.
I would add if you do use a grinder (you
can safely grind with a carborundum grinding wheel) LIGHTLY is
the operative word. Also invest in a wheel dresser (diamond point or western spur revolving type) which keeps the wheel true round and removes clogged particles. Most people try to grind on wonky clogged up wheels that need pressure to cut, so causing the build up of heat that WILL ruin your steel blade's. I have safely ground dozens of plane irons, chisels (even delicate ones) axe's adzes etc and have never burnt any. Keep a pot or jar of cool clean water right next to your grinder and dip-cool after every 1 or 2 passes, dab dry with old towel. Check very often using your palm to test temp. And don't rush.
If I had the £££'s I'd get the tormek wet wheel (quieter than carborundum)but well you know how it is.
When you come to re-haft your axe I would suggest using air-dried cleft ash (not a ready made from a shop) Cleft is split out the log not sawn so it follows grain instead of crossing it and is stronger. There are sites that show you exactly how, basically a lot of patient work with spokeshave, knife, files to fit haft TAP (tightly as possible), couple of oak wedges voila.
Oh and don't get fooled by that daft notion of slingin the axe in the woodburner to burn the old wood remains out-that will definately ruin it.
Good luck with your axe Andy whatever method you eventually use; nice to see a fellow scavenger at work!!
:wave: