Those numbers are simply how much your attack/defense will change when you equip a different weapon. So if you are at 50/25 and select a 60/40 weapon, the numbers would be blue and say +10/+15.
This 'thank you' is belated by like 7 months, but nevertheless, thank you! I actually forgot that I'd posted this, or else I would've followed up on it. I figured out the purpose of the arrows about a couple months or so after posting, due to the fact that I've since gotten heavy into RPGs. The majority of them use the same basic structure and battle jargon, so I'm much more educated when it comes to reading stats. But no matter, I appreciate you taking the time to help with my problem. :-)