Can we talk "ECHO KNIGHT"?

I'm just starting to play one. A few things are a bit unclear. I would appreciate input from people which have played them and can give me some tips. Thanks

You might check out this thread. 
https://www.dndbeyond.com/forums/class-forums/fighter/64918-an-echo-knight-faq-frequently-asked-questions

Thanks, there's obviously a lot to it. 

I'll planning to go with a DEX based fighter, instead of strength. I'm considering "dueling" with Rapier and Shield, to always get a +2 to damage. 

Any thoughts on this and recommended Feats? I'm considering MOBILE, and maybe Aberrant Dragonmark, to get a couple of spells.