I also will laugh at your calamity; or, more accurately, in the time of your calamity; as in the Vulgate, in interitu vestro ridebo. The preposition prefixed to the substantive b'eyd'chem ( בְּאֵידְכֵם) refers to the time, or state, or condition.
In the time of their calamity wisdom will exult or rejoice. The LXX; τῇ ὑμετέρᾳ ἀπλείᾳ ἐπιγελάσομαι, however, favours the rendering of the Authorized Version. Calamity ( אֵיד, eyd) is heavy overwhelming misfortune, that which oppresses and crushes its victims.
The terrific nature of the punishment of the wicked is marked by a succession of terms all of terrible import—calamity, fear, desolation, destruction, distress, and anguish (Proverbs 1:26, Proverbs 1:27).
When these come upon them, then Wisdom will laugh and have them in derision. The verbs "laugh" ( שָׂחַק, sakhak) and "mock" ( לָעַג laag) are the same as in Psalms 2:4, where they are rendered "to mock" and "have in derision."
When your fear cometh; i.e. has actually arrived. Fear ( פַחַד, pakhad); here used metonymically for that which causes the fear or terror (id, quod timebatis, Vulgate). There is a similar use of φόβος in 1 Peter 3:14.