I have a Character and a Dagger with Attribute DAM_Fight
Character DAM_Fight = 3
Dagger DAM_Fight = 2

I have a turnscript to calculate how much damage the Character does:

game.pov.DAM_ThatIDo = game.pov.DAM_Fight
foreach (object, GetDirectChildren (game.pov)) {
  if (HasInt (object, "DAM_Fight") and GetBoolean (object, "visible")) {
    game.pov.DAM_ThatIDo = game.pov.DAM_ThatIDo + object.DAM_Fight
  }
}

I have a command 'harm #object#' which is supposed to deal this DAM_ThatIDo value, based on its own and the daggers DAM_Fight combined.

if (HasAttribute(object, "LIFE_C")) {
  object.LIFE_C = object.LIFE_C - game.pov.DAM_ThatIDo
  msg ("You have ritually wounded " + GetDefiniteName(object) + ".")
}

But for some reason, instead of doing 5 Damage, it deals 12.

I have another Character whose DAM_Fight = 1.
However, when she wounds with a Dagger her 1+2 comes out as 10 Damage.

Any idea what is going on?

I have set up a Status Panel item to show the DAM_ThatIDo value, and it shows an increase to 12 as soon as the Dagger is taken, so it is not a problem with the 'harm #object' command...

Are there any other scripts modifying DAM_ThatIDo?

Are you sure that DAM_Fight has the correct values?

Those are the first things I would check in this situation. I don't see a problem with your code.

I might also try adding "breadcrumbs"; temporarily changing the turnscript to something like:

game.pov.DAM_ThatIDo = game.pov.DAM_Fight
msg ("Calculating DAM_ThatIDo. Initial value: " + game.pov.DAM_ThatIDo)
foreach (object, GetDirectChildren (game.pov)) {
  if (HasInt (object, "DAM_Fight") and GetBoolean (object, "visible")) {
    game.pov.DAM_ThatIDo = game.pov.DAM_ThatIDo + object.DAM_Fight
    msg (" - Adding damage for " + GetDisplayAlias(object) + " (" + object.DAM_Fight + "), total now:" + game.pov.DAM_ThatIDo)
  }
}

That might seem like overkill, but trying the game with that running will give you a clear idea of exactly where in your code a problem is creeping in.

(In my code, I use JS.console.log rather than msg for error messages; so the debugging is hidden until you press Ctrl+Alt+J to show it… but I'm not sure whether that will work with the desktop editor)

It was an incorrect DAM_Fight somewhere from testing health loss earlier xD