PLD12 / WLK 5 / FTR 3 is probably the best split for a char like this. Start with FTR 1 for CON save proficiency to help concentration, then go 3 WLK and 6 PLD.
Be a human to start polearm master and pact of the tome for shilellagh (CHA). Take Dueling and Defense Fighting Styles. Eventually pick up FTR 3 Champion for 19-20 crits and Action Surge.
By taking oath of vengeance, you'll get Haste at PLD 9, which you can cast with your WLK pact magic slots.
Your action economy with haste will be 3x normal attack (1d8), 1x bonus (1d4) and 1x reaction a turn using your CHA as your damage stat. Each attack will have an additional +1d8+2 bonus from fighting style and improved divine smite. You will have a minimum of 23 AC with plate and a shield defense fighting style and haste and all your saves will benefit from your CHA bonus.
When attacking with advantage you will have a 19% crit chance.
Your pact magic (2x lvl 3 slots), action surge, channel divinity and second wind will all come back each short rest.
You will have 3 WLK cantrips and 3 WLK invocations.