But I seem to recall that reducing didn't help my fire giant vault much.

Spear doesn't really have major downsides at hero imho. Most of the things you'd expect to cause problems (Eg kot) don't really, in practice. Taking that example, it means you try not to aim at the assassin (your hit all from blood lust and your spells will do enough) and you can flee if by some miracle he breaks your wrist.

Maybe poisons would be a danger but poisoners are relatively scarce (and as a scarab hero you can largely ignore them too).

Spear actually tanks pretty well and your damage is reasonable. It isn't burst damage but it is steady, and you can often toe to toe a fire giant with equal preps.

What is totally useless now is lashes of the slave. As tsal I switched to whip in order to be free to cleave the lich, and lashes did decimates to the huntress etc when I had over 100 charges. And it didn't prog much either. I'm not talking about unholy prog, just the prog from the skill.

It was nerfed way too hard. I actually think they should have kept in its ability to remove no disarm shields etc. Just limited the damage to (say) dismembers.