Few upgrades, since prot paladins got quite revised in last patch.
You NO LONGER needs spelldmg from gear, which has been removed from prot - pala specific items anyway, as You get spelldmg from your stamina (30% of your stamina will add to spelldmg) - Touched by the Light talent, with a decent gear You should get around 300 spelldmg ( i have around 370 on my protadin) which is enough to tank almost everything.
As said before - you no longer need spelldmg, so u no longer need spelldmg weapon! Grab yourself a decent weapon with high dps, stamina, and tank-stats (such as def, dodge/parry/block etc). Why high dps u may ask? New talent! Hammer of the Righteous, which causes 4x ur main hand weapon damage as holy damage, generating loads of threat!
Best options(and easy to get) for beggining to tank are: Crystalline Kopesh from Durn the Hungerer quest, Gromtor's Charge from Cipher of Damnation chain, or Inuuro's Blade from SSO rep.
Seal of Vengeance became much more better for threat, then Seal of Righteous from what I noticed, and i prefer to use that one while tanking, also, use HoR whenever it's cooldown is ready, as its ur main thing to get threat with.
Crushing blows was removed from game but.... critical hits werent! So You should still get 490 defence, even tho its much harder now, since Blizzard removed that +20 def rating talent.. Investing in enchantments is best way to achieve lacking defence.
***def enchants***
+15 def on chest,
+12 def on bracers
+glyph of the defender - CoT rep 16 defense rating and 17 dodge rating
+ Vindicator's Armor Kit, 8 def rating on the chest, legs, hands or feet
+ scryers / aldor enchantment - 15 defense rating and 10 dodge, or 10 def rating and 15 dodge rating
Also, dont forget about def/sta gems!
For a weapon enchantment - I would use +20 str (block value) or mongoose, If you have decent weapon, and money for it (im using mongoose on Cleaver of the Unforgiving from ZJ).
GL for gearing and using your tank!