This is the 718th most frequent Icelandic word.
vikna
"Vikna" means "to become cracked" or "to develop cracks."
Here, 'viknaði' is the past tense form of 'vikna', used to indicate someone physically softening or weakening over time.
Hann viknaði eftir þrjá daga í rúminu.
He softened after three days in bed.
In this sentence, 'viknum' is the present tense plural form, implying yielding or giving way emotionally or psychologically.
Við viknum þegar við hittum persónulega reynslu.
We yield when we encounter personal experience.
The usage of 'viknaði' here reflects a physical bending or giving in due to force or weight.