How do you increase a Blade's strength?
There are a lot of merc missions that require a certain strength to proceed with them. Since this seems to be the only thing in the game using strength, is it right to assume that just sending them on merc missions will increase their strength? Or do they have to be the leader, or is it entirely random?
I don't quite understand the correlation, but for the lot of blades I checked, it seems to be +/-2 from the number of orbs they've unlocked in the affinity tree. So, the safest bet is to just unlock more orbs and strength will go up as a result.