There is nothing in the source code of the damage calculation in pvp that defines a defcap.
Actually, basic defense isn't really that important at all in pvp.
I seen that the defense of a character gets calculated to a defense level and the damage gets calculated based on that.
Code:
if (adef >= 5 && adef <= 8)
awdamage /= 2;
else if (adef >= 9 && adef <= 12)
awdamage = awdamage * 3 / 10;
else if (adef >= 13)
awdamage /= 10;
if (ddef >= 6 && ddef <= 10)
{
dresist /= 2;
dresist2 /= 2;
}
else if (ddef >= 11 && ddef <= 15)
{
dresist = dresist * 3 / 10;
dresist2 = dresist2 * 3 / 10;
}
else if (ddef >= 16)
{
dresist /= 10;
dresist2 /= 10;
}
Something like that, just that is for adultserver and probably not the same