The meaning of the name Mercer is an English and Scottish occupational name used for a textile worker, often who works with more expensive fabrics.
Derived from the French word Mercier, or Latin Mercarius or Merx (two very competitive alternative naming options too I think). I personally love the idea of a little Merx. Totally cute on a girl with the nickname Mercy as well.
Mercer fits nicely with names Olivia, Macy and Eliza.