Need Help Against the Final Boss [Tonberry Rune Knight]

[Sauken]

Dump:
http://angband.oook.cz/ladder-show.php?id=24211

So here's the issue.

Generally, J seems to be burning through my staff of healing charges and potions faster than I can burn through his HP. I'm wondering if there's something I need that I don't have yet, or if my strategy is wrong. Should I just try to banish every time he summons, or teleport away and let him come to me? Is there anything Rune Knights can do that I'm not taking advantage of? And do I have enough healing/*healing/life, or should I grind for more? Is there any way for me to get a better weapon, reliably? Do I just need to kill more uniques? Are there any quests that won't kill me, that will give me something I need?

I've had a lot on my mind, as you can tell.
Thanks for the advice

Edit: Game has been won! Check the dump for some comments. I suspected this would happen (me finishing the game before anyone has a change to help)... but it was worth a try!