About you fu 有孚 see here.
窒惕: Many assume that zhiti 窒惕 forms a fixed phrase, and I follow that same route although this is by no means an established fact – we do not find this phrase in other books so we don’t have any reassuring references for it. But this passage consists of several set phrases: 有孚, 中吉, 終凶, 利見大人 and 不利涉大川, which makes the possibility that zhiti is a fixed phrase very likely (Lu Deming 陸德明 suggests the text should be punctuated differently: as “有孚窒.” and “惕中吉.”). But we can only guess at its meaning. To make matters more complicated the variant texts all give other characters for this phrase:
Let us start with zhi 窒 and its variants. There is a common theme, some sort of overlap, in some of the meanings that these characters have. I have singled these out:
窒: perverse behaviour; disagreeable character (乖戾；執拗)
Zigong said, “Surely even the better person must have hatreds? Confucius said, “He has hatreds. He hates those who point out what is evil in others. He hates those who dwelling in low estate revile all who are above them. He hates those who love deeds of daring but neglect propriety. He hates those who are active and venturesome, but are violent in temper.
(Lunyu 論語, tr. Arthur Waley)
洫: ruin, corrupt (敗壞). Also a loan for yi 溢, ‘excessive, overdo, go beyond the normal limit’.
懥: anger, resent, hate (憤怒；憤恨)
When you are angry, you cannot be correct.
(Daxue 大學, tr. Charles Muller)
The Kangxi Zidian 康熙字典 says that 懫, which is used in the Xiping Stone Classics 熹平石經 version of the Yijing, is a variant of 懥.
The general idea that speaks to me here is that of outrage, going over the limit, undesired behaviour. This has to be 惕: ‘watched out for’, you have to be watchful and alert, but the anger also has to be ning 寧, ‘pacified, calm down’, as the MWD text puts it.
Although anger and outrage is to some extent justified it should not be taken to the limit, nor should it be used all the way.
There is blessing and protection.
To temper anger halfway is auspicious. At the end is inauspicious.
Advantageous to see the great man.
Not advantageous to wade through the great river.