Great question! This confused me for a long time.
The in-battle sword icon is your attack value, or what damage you’d do ignoring the defense of your enemy. It’s actually a combination of your medal strength, your Chips on that medal, and the multiplier slot it’s in.
For instance, my Terra is 7338 +1000, in a multiplier slot of x2.35 on Three Wishes. In battle his attack value is 19,594, which is just 8338 times 2.35. It’s a handy measurement, so you know how much damage each medal is likely to do in-battle.
Friend medals are a little more complicated. There’s no on-screen representation of a multiplier slot for a friend medal, which is why they are often thought of as less powerful. But there is a multiplier for each Friend medal factored in based on keyblade level. Roughly, a level 2 keyblade has about a x1.04 friend slot, while a level 20 keyblade has about a x1.30 friend slot.
My friend’s TVA+1000 is as follows on different keyblades:
MoG +5: 9050 ~ x1.13
SL +22: 11076 ~ x1.38
LL +25: 13198 ~ x1.64
DR +26: 13487 ~ x1.68
Special Attack Bonus and guilt are not factored into any of these, since it’s an optional multiplier in battle.
I hope this helps! (I actually learned a little bit on Friend medals while confirming this!)
<3 KCM
P.S. Anything above 7000 base strength is very very good. Often base strength is what makes a medal better or worse than another.

