I tanked as a paladin on normal classic in all dungeons but LBRS/UBRS. The two fights I remember having trouble with was Princess in Mara and Shade of Eranikus in ST. Princes does her knockback and fear which means limited melee uptime and ranged dps can easily pull threat. With no taunt in HC that is a pretty big disadvantage. On Shade he puts the tank to sleep and drops aggro. You need a taunt to pick him back up, which again, big disadvantage.
Other than the lack of taunt, everything else you can do just as well or better than Warriors and Druids. Going engineering and using grenades to range pull is a must. Judging righteousness is generally enough snap threat. Using wizard oils will ensure everything is glued to you. Mana isnât really an issue if you learn how to use seal/judgement of wisdom, down rank spells like consecration, use mana pots, and use a threat meter to know when you need to use spells. Even if you do need to drink, it gives an opportunity for the healer/casters to drink to and your mana pool is so small that you will generally get a full bar faster than others in your group.
I always liked the 11/32/8 build, getting consecrate in the holy tree first, then deep prot, and the final points in the ret tree for cheaper seals and some parry. Iâve never done a 31/20/0 build to tank but it definitely would have better single target aggro. As you level up you will be missing some damage mitigation talents in prot which does matter for how large a pull you can do and for conserving healer mana. I personally wouldnât go the funky tri-spec the OP mentioned. Youâd be missing reckoning which is amazing for extra seal/judgement procs and holy shield which is a good mitigation/threat ability.