Structure of "c'hai"

Question

When using ci as a demonstrative pronoun it replaces the object completely, for instance: Sei mai uscito con la mia sorella? Non, non ci sono mai uscito, so in the answer there is no information about the object (gender, quantity, etc), but everything is absorbed by ci. Now, if we say

noi pregheremmo lui de la tua pace, poi c'hai pietà del nostro mal perverso.

1. Is c'hai a valid contraction of ci hai? and
2. if we use ci then shouldn't we suppress the object to avoid redundancy? That is, isn't poi c'hai pietà enough, or poi hai pietà del nostro mal perverso enough?

Answer 1

The correct way of reading the words is poi c'hai pietà del nostro mal is poi che hai pietà del nostro mal. In modern Italian, the first two words are more often written as a single one, poiché, meaning “since, due to”. Hence, the clause means simply something like “...since you have mercy on our wicked suffering” (not an actual nice translation, since English is not my mother tongue).

Out of curiosity, this is how the sentence appears in Dorothy L. Sayers's translation of Dante's Comedy:

...we would entreat Him for thy peace,
That pitiest so our pangs dispiteous!

Notice that for 99% of the history of Italian language, c'hai has been the contraction of che hai, as here. Using it for ci hai is a recent and debatable development.