Spartan

The Spartan achetype is a master of spear and shortsword, while using their shield both offensively and defensibly. you gain features in this archetype first when you choose it at 3rd level and again at 7th, 10th, 15th and 18th level.

Phalanx

starting at 3rd level while wielding a shield and wearing Medium armor you have learned to protect yourself and your allies better with your shield. Your shield gains a +1 AC bonus, and any ally within 5 feet gains any AC bonus your shield provides. if any ally within 5 feet of you are also wielding a shield that ally also gains use of this feature and you are both considered in half-cover.

Shield Bash

starting at 7th level while wielding a shield and wearing medium armor, you can use one of your attacks to make a shield bash. This attack deals 1d6 Bludgeoning damage and attempts to knock the enemy prone. The target must succeed on a strength saving throw against a DC equal to 8 + your proficiency bonus + your strength modifier or be knocked prone.

you can also use 2 attacks to make an improved shield Bash that deals 1d8 Bludgeoning damage and attempts to both stun the opponent as well as knocking them prone. DC is the same as normal shield Bash.

Hoplite

Starting at 10th level you have become a master of the Spear and shortsword. when you are wielding a shield and either a spear or a shortsword you gain +2 to hit and you damage is increased with an extra damage die.

Hellenic Champion

Starting at 15th level whenever an ally affected by Phalanx is attacked you can use your reaction to become the target of the attack instead. You Phalanx now also gives you and your allies a bonus to Dexterity saving throws equal to the AC bonus of your shield (including the +1 from phalanx)

Hero of Thermopylae

Starting at 18th level you have become an unkillable menace on the battlefield. when an attack would reduce you to 0 hit point you instead are reduced to 1 hit point and you enter a battlerage for 2 rounds.

when in a Battlerage you are immune to any effect that would prevent you from acting or moving (including unconscious), you gain a bonus to AC and attack of +5. and you deal an additional 10 damage on every weapon attack. if you are reduced to 0 hit points again during the battlerage you do not fall unconscious, but you do if you have hot been healed when the battlerage ends. 

this feature can only be used once every long rest.