Could the name be changed as well? It essentially needs to be created from scratch, just to avoid the hassle of copying all the information from the old hero. When I created characters for myself, I didn't have any problems.

Added 8 minutes later
And the function also needs to include a check for accuracy:

setCount = 0;

function setInfo(object, hero)
    setCount = setCount+1;
    heroname = hero;
    sleep(5);
    if IsHeroAlive(heroname) ~= true then
        return;
    end;

    if setCount == 1 then
        MessageBox(GetMapDataPath()..'count1from8.txt');
    elseif setCount == 2 then
        MessageBox(GetMapDataPath()..'count2from8.txt');
    elseif setCount == 3 then
        MessageBox(GetMapDataPath()..'count3from8.txt');
    elseif setCount == 4 then
        MessageBox(GetMapDataPath()..'count4from8.txt');
    elseif setCount == 5 then
        MessageBox(GetMapDataPath()..'count5from8.txt');
    elseif setCount == 6 then
        MessageBox(GetMapDataPath()..'count6from8.txt');
    elseif setCount == 7 then
        MessageBox(GetMapDataPath()..'count7from8.txt');
    elseif setCount == 8 then
        MessageBox(GetMapDataPath()..'count8from8.txt');
        GiveArtefact("heroname", artifact1Id);
        GiveArtefact("heroname", artifact2Id);
        ChangeHeroStat("heroname", STAT, count);
    end;
end;

Trigger(OBJECT_TOUCH_TRIGGER, 'dragonGuard1', 'setInfo');
Trigger(OBJECT_TOUCH_TRIGGER, 'dragonGuard2', 'setInfo');
Trigger(OBJECT_TOUCH_TRIGGER, 'dragonGuard3', 'setInfo');
Trigger(OBJECT_TOUCH_TRIGGER, 'dragonGuard4', 'setInfo');
Trigger(OBJECT_TOUCH_TRIGGER, 'dragonGuard5', 'setInfo');
Trigger(OBJECT_TOUCH_TRIGGER, 'dragonGuard6', 'setInfo');
Trigger(OBJECT_TOUCH_TRIGGER, 'dragonGuard7', 'setInfo');
Trigger(OBJECT_TOUCH_TRIGGER, 'dragonGuard8', 'setInfo');