What is something that you feel most 2nd lieutenants lack?

Too easy-experience. Everyone likes to pick on the Butter-Bar (and for good reason), but honestly, most will mature into competent officers given half a chance. The small percentage that are complete wastes of space generally don't make it very long. You simply cannot "make" tactical geniuses, or imbue the highest standards of personal leadership across four years at ROTC or the Academy, let alone shorter periods in OCS... but you can plant the seeds. Sadly, I believe enlisted, or commissioned, we often end up canning otherwise promising officers and enlisted members for relatively minor errors early in their careers.

Humility and social skills.

Wisdom. But that (hopefully) comes with experience. The biggest wisdom gap I see is understanding when to be patient, and when to be urgent.

The surefooted composure of experience.

I once had a very famous 4-star general tell me that Second Lieutenants were nothing more than privates with college degrees.

They lack experience - many are just out of college & OTS and really have no experience in leadership, management and mentoring. Good NCOs & SNCOs will mentor and support. A young LT may be a future commander is they want it.

Just learn from your more experienced NCOs, SNCOs and senior Officers. Be a sponge and learn all you can.

Facial hair

In a word - HUMILITY. In my brief military experience, many 2LT's seemed to be quite impressed that EM's of vastly superior knowledge and experience have to salute them and address them as Sir, something that many have probably never experienced before. I experienced that with a 2LT (OCS "90 day wonder") who was quite impressed with himself and loved to make others' lives miserable. I also believe that in this generation of entitlement, the humility issue has become even more pronounced. Many young people feel that they already know it all, and should be accelerated to a higher position than they're actually far from qualified to fill.

One word - Experience - and a desire to become better!