The other day I saw a complaint about arm flab or the classic bat wings.  It started raining and apparently their child used their arm flap to protect themselves from the rain….it worked.  It’s common, and frankly if it’s extra skin obviously you have bigger problems that you need to consult with a professional about.  They can reduce extra skin, it just takes more extreme methods generally speaking. 

However, if you are talking about fattier and flabbier arms in that direction, you can start carrying weights  as you walk if you don’t have the extra time before or after to do something else.  But if you do, you can use certain weight lifting routines in general to tone the arms at large.  There are some that are less effective than others.  But generally speaking, if you work the arms in general, over time they will all develop evenly instead of leaving you with disproportionate arms or muscles in general.  If you are just looking for toning, of course stick to few repetitions with light weights.  However, heavier weights would be more appropriate should you be of the mindset to actually build greater masses of muscle in general.  It depends entirely on your particular goals.