Sorry to hear about Ignatow's death! It sounds like Pitspawn Fouldog has claimed another life- he's caused more than his fair share of deaths. Were your cold resists boosted by thawing potions? I always stock up when visiting the Jail 2 because of him. And to feed to the merc.
I had Ignatow a while ago, in A4 norm. I didn't have him long but at that point he was cruising easily. I played most of the act at /players 8 but I did go down to /players 3 I think for the Chaos Sanctuary, as I was worried about expensive merc deaths and IM for myself of course. I only put 3 levels on him, but it's a short act and level 34 is fine for Diablo, particularly when the experience-fest of Act 5 is coming up. He had the Conversion point on him when I got him and I meant to try it out (I wasn't sure if it could work with a bow), but I forgot to try. I got an El from the forge drop.
I put 4 points in Conviction and 1 in Resist Lightning. The RL point boosted max lightning resists to 77, since it's the even hard points in the resist auras that boost max resists.
I used Coldsteel Eye + Ward, Skins of the Vipermagi and Peasant Crown and cruised through the act. For the CS, I bumped down the player count and switched to Raven Claw when there were cursers in range. It took a while, but I wanted to be careful. After clearing the CS and popping Lord de Seis, I bumped the players back up and the rest was no problem. I can't remember if Diablo killed the merc or not.
I agree that with Avengers it's good to put points in Conviction before Vengeance (Conviction doesn't increase the mana cost and is better bang for the buck) and also it's good to put points in RF and RL before Vengance, for the passive boost. It looks like you were going two-handed, which unfortunately means the Holy Shield didn't do you any good. I take it you didn't have any suitable one-handed weapons, as HC two-handed is trouble, in my opinion!
Ignatow upon arrival in A4 norm:
L31
S66 D61 V73 E40
4 Zeal, 4 Veng, 1 Conv, 1 HS
Holy Freeze 2, Holy Shock 1, Conviction 1
Resist Fire 3, Resist Cold 3, Resist Lightning 3
Ignatow upon departure:
L34
S 66 D 61 V 88 E 40
4 Zeal 4 Veng 1 Conv + HS
HF 2 HS 1 Conv 5
RF 3 RC 3 RL 4
gear that I remember: Coldsteel Eye, Ward or Whitsan's, can't remember, Raven Claw on switch
definitely: Peasant Crown, Skins of Vipermagi, Mahim-Oak Curio (almost all of my characters have worn those!)