之: marks preceding phrase as modifier of following phrase; it, him her, them; go to
This function of 之 is different from the one in your quoted text.
之 in [Verb + 之] functions the same as a pronoun
Example: "逆我者，殺(之)" = "the ones who against me, kill (them)"
In this sentence, the verb 殺 precedes 之, therefore, 之 functions as the pronoun of the noun 逆我者
要走好人生之路 = need to properly walk life's road
之 in [n + 之 + n] functions the same as [n + 的 +n]. It is used between two noun phrases to show possession or relation
Example:人生之路 = 人生的路 = "life's road" or "the road of life"
In this example, 之 is placed between two noun phrases '人生(life)' and '道路(road)' to connect them. Indicates 人生 possess 道路 (similar to [ 's ] in English)
之 in this role is the literary (classical) counterpart of 的.
Saying 人生之路 instead of 人生的道路 make it sound more literary (classical) than colloquial. Modern Chinese is the mix of colloquial and literary (classical) terms
and sometimes we want to sound more literary
Notice: the noun after 之 is usually a single character word
Another way to see the function of 之 is 之 [used as a dummy pronoun for emphasis], which would make functioning like a verb particle
Example: "逆我者，殺(之)" = " kill (!), the ones who against me"