This is the most beautiful eye as Arabs think. As for the deficiency in woman's religion, it is not an insult against women but it is an encouragement to them to do more good deeds. Since a woman can neither pray nor fast during her menses, this means she needs to do other good deeds to get reward instead of the reward that she missed during her menses. Charity is a good example. The answer is because Allah is merciful to women.
Some references fully equate the testimony of males and females.
When you deal with each other in transactions involving future obligations in a fixed period of time, reduce them to writing. Let him who incurs the liability dictate, but let him fear his Lord, Allah, and not diminish aught of what he owes. If the party liable is mentally deficient, or weak, or unable himself to dictate, let his guardian dictate faithfully. And get two witnesses out of your own men, and if there are not two men, then a man and two women, such as you choose for witnesses so that if one of them errs, the other can remind her. And Allah is well acquainted with all things.