The arrow weight would be the weight per inch in grains X the number of inches the shaft is and then add the weight of the insert, nock and insert if any is used, the weight of the fletching and the weight of the point. Just measure each arrow on a scale, I use a reloading powder scale for mine. The brace height on your Tribute is 7.5 inches and the LX I believe is 6 5/8 inches,, lot of difference in brace height
