No blue helms unfortunately.. unless NL dupe bone helm but think I’m wrong.

Gloves, armors typically add mana which triggers it and damage to mana on shield makes them blue

https://forums.d2jsp.org/topic.php?t=68614511&f=21

ofc blue helmets are possible, nova/frost nova proc is a possible affix

thats not correct. the link considers multiple examples of items that are only possible in expansion, but not classic (like circlets, barb/druid helms, upgraded item etc)

Here's a good tool to figure out hypothetical items and colors:

https://tools.harrogath.com/affixcalc.html#namesuf=69&classid=373&;