What holy melee could use:
- more defense, exclusive for melee (compared to spearzon for example where lionheart is comparable to lioness, zons have balance, pala lacks that big chunk of flat defense, pala shields are relatively low defense too)
- faster 2h weapons.
- buff single target skill (and actually test it lategame until it is very solid)
- buff/tweak colosseum so it is really worth using, makes gameplay less monotonous (its a buff so make it op because this skill has been unused since it was introduced 20 years ago)
- potentially buff endgame scaling of plague (it starts very strong and is fine, but if you take fully geared lategame pala with all charms, it tickles ubers)
But I think bottom line with holy melee feeling weak in lategame was low defense, which makes you quite fragile. If you could get barb runemaster levels of defense then it could stay alive in harder ubers, and people would start complaining about damage
mainly trying to kill necrobot with plague carried by 50% wdm skill, thats like small fraction of what snake stance barb can do in current patch. If its tweaked that lategame, with all proper gears and pierce, you can actually 1shot uberlevel white enemies with plague, holy melee will be considered as back to viable.