At least two characters are Commanders: Crow Gideon and Phineas Kidd.
Examples of Phineas using Commanding: here and here.
The first to talk about Commanding in the comic is Hazard: p.182
Phineas commanding
Phineas memories about Commanding (probably Crow Gideon talking): p.230 and further.
Also, Phineas talking to Ulrich: p.263
and p.344