Congratulations, this is almost completely wrong.
Firstly, the 1d4 bonus action attack is not an off hand weapon, so you don't need Two Weapon Fighting in order to add your ability score to damage.
Secondly, it's a 2H weapon, so it benefits from the Great Weapon fighting style, which is especially strong with 2d4, increasing the average damage from 5 to 6, and the bonus action damage from 2.5 to 3.
With the feat, it gives the finesse property to the weapon, enabling sneak attack and elven accuracy. It's comparable to the Duel Wielder Feat with 2 rapiers (4.5 average damage), doing more damage on the main attack but less on the bonus action attack (which is all together better since one usually has more main attacks than bonus attacks).
Polearm Master (with Great Weapon style) is superior if you have the strength, but as an elf, your dexterity is probably higher.