Try this. Found it here: http://eugenyus.rudtp.ru/en/list_freescript.php

//(c) Eugenyus, 2012, v1.0, Eugenyusbudantsev@gmail.com
//Поиск-замена толщины контуров ячеек таблиц

var talert = "The selection does not contain tables.\nSelect text or frame with tables";
try{var myT = app.activeDocument.selection[0].tables;}catch(e){alert(talert);exit();}
if (myT.length == 0){alert(talert);exit();}
var w = new Window ("dialog","Cells Stroke Weight");
w.alignChildren = "left";
var pan1 = w.add("panel");
pan1.alignChildren = "left";
var pan1g1 = pan1.add("group");
var ft = pan1g1.add("statictext",undefined,"Find: ");
ft.characters = 12;
var findWeight = pan1g1.add("edittext",undefined,"1");
findWeight.characters = 4;
pan1g1.add("statictext",undefined,"pt");
var fAll = pan1g1.add("checkbox",undefined,"All");
fAll.onClick = function(){findWeight.enabled = !fAll.value;}
var pan1g2 = pan1.add("group");
var ct = pan1g2.add("statictext",undefined,"Change To: ");
ct.characters = 12;
var changeWeight = pan1g2.add("edittext",undefined,"0.5");
changeWeight.characters = 4;
pan1g2.add("statictext",undefined,"pt");
var pan2 = w.add("panel",undefined,"Search");
pan2.alignChildren = "left";
var aHor = pan2.add("checkbox",undefined,"Horizontal Lines");
aHor.value = 1;
var aVer = pan2.add("checkbox",undefined,"Vertical Lines");
aVer.value = 1;
var bg = w.add("group");
bg.add("button",undefined,"OK");
bg.add("button",undefined,"Cancel");
if (w.show() != 1){exit();}

var fw = Number(findWeight.text.replace(",","."));
var cw = Number(changeWeight.text.replace(",","."));

var str = "";
if (aHor.value){
str+="if (myC[j].topEdgeStrokeWeight == "+fw+"){myC[j].topEdgeStrokeWeight = "+cw+";}\r";
str+="if (myC[j].bottomEdgeStrokeWeight == "+fw+"){myC[j].bottomEdgeStrokeWeight = "+cw+";}\r";
}
if (aVer.value){
str+="if (myC[j].leftEdgeStrokeWeight == "+fw+"){myC[j].leftEdgeStrokeWeight = "+cw+";}\r";
str+="if (myC[j].rightEdgeStrokeWeight == "+fw+"){myC[j].rightEdgeStrokeWeight = "+cw+";}\r";
}
if (fAll.value){str = str.replace(/(.+?\{)(.+?)(\})/g,"$2");}

for (i=0;i<myT.length;i++){
var myC = myT[i].cells;
for (j=0;j<myC.length;j++){
app.doScript(str,ScriptLanguage.JAVASCRIPT);
}
}

Agreed. This would have been a great time saver for my project.

Indeed very much needed.