Often Paladins are overlooked because they’ve kinda an awkward role right now, they do have very nice support and dmg is good too, but often their support is not needed or does more harm than good (like using Barrier in the middle of a room spreading the mobs, hindering your aoe dps mates), you can use it no problem, but you’ve to be aware of where you use your barrier because you can screw up your team.
As for the tank part, Paladin isn’t a tank at all, a tank is a Peltasta which is in the Swordman tree who has an ability that can group monsters, Paladin can’t do that, the blue icon simply means they’re a defensive support because they provide just that, defense, so you’re simply a defensive healer, not a tank, keep that in mind 
Now onto the build if you finally decide to make it:
Cleric C2 > X > Paladin C3 > X > Inquisitor
That’s the core of the build, both X are just personal preferences or what you want your Paladin to be doing 
First X can be either Diev, Cleric C3 or Priest, first one for Laima to reduce CD of your skills and your allies (also free teleport), Cleric C3 means more heals (often overkill but can be useful if you’re the only cleric in the party) and Priest for Ress (if you intend to go ET and you’re going to be the only cleric there it’s really helpful).
Second X is either Kabba, Monk, Oracle or PD, Kabba for Ein Sof so SP regen (can be helpful since Paladin’s skills wastes a lot of SP but then again we’ve pots which are cheap), Monk for an offensive option and filler skills, Oracle or PD for support.
As for Stats is about 50 CON (you can go 0 CON if you wish), some SPR if you think the SP is going to be a problem (not that high tho, 30-40 if anything, but if you think SP pots are enough not needed) and rest goes into STR since your main dmg abilities scales with it.
My personal favorite is Cleric C2 > Diev > Paladin C3 > Inquisitor.