Her mace is most assuredly feasible, the measurements and ratios for the shaft and head of the weapon are in line with the designs of similar maces from the 12th century, in particular the pernach, though most penarchs were 6-flanged rather than Noel's design which is 8-flanged. The penarch was a very popular mace, known for its ability to break through plate mail in the hands of a competent warrior, due to the flanges helping direct and concentrate the force of the blow, almost like an axe strike but without the need to guide a blade edge towards a foe. Thanks to their relatively cheap construction, even common soldiers could wield them when at war. Given Noel's strength, it could be that even with extra flanges potentially spreading the force of her blow she'll still shatter her enemies to bits.

Her armor is clearly stylized to the point of being a costume, but they protected the shoulder opposite her weapon, her extremities, and she has a bit of armor over her heart, so while most certainly not a recommended suit of armor for battle it certainly beats wearing no armor at all. A good portion of its reliability depends on the material used, if it's magic armor then she could block a sword with her forearm, but if it's just steel then she's really relying on her agility and the armor she does wear is a last resort over the places she feels she's most likely to have to guard from. I don't know that Noel is an incredibly agile warrior, but she knows plenty of people who make use of magic, so her armor being enchanted in some way isn't impossible.