Surely it should be obvious to the dimmest executive that trust, that most valuable of economic assets, is easily destroyed and hugely expensive to restore.

第一个that 引导主语从句被外置，形式主语是it。

第二个that 是指示代词，用在最高级之前，意思等于the，具有强调意味。被形容词最高级修饰的名词被省略：the most valuable thing of...，作trust 的同位语。

我把句子稍微改写一下，即可理解：

Surely it should be obvious to the dimmest executive that trust, the most valuable (thing) of economic assets, is easily destroyed and hugely expensive to restore.

由此看出，of 跟valuable 无关，而是of economic assets 作定语，修饰省略了的thing。