This Lucy and Brandish discussion is like Gray and Ultear & Lyon. In Gray's case, both Ultear and Lyon aged to what they are like now, while Gray got trapped inside Fairy Sphere for 7 years. Gray was introduced as a 18 yo boy in the beginning of series. He is now 26, but physically (and maybe biologically) still 18. Both Ultear and Lyon used to be villain, and turned into good chars. I still remember Ultear said she is like Gray's oneesan. And if I remember correctly Lyon was older than him.
I still think Brandish was born earlier than Lucy, but who knows. Lucy is 17 when got introduced, and now she is 25 (physically still 17). Brandish seems to be 1 year or 2 older than Lucy. So maybe she is 26 or 27.
Brandish is like 25 so just a guess that would make Dimaria around the same age too of 25... that's one of the reason I've been enjoying these villians.. most of them look around the age of team Natsu but are all op as shit... and in genereal seem fun to be around lol. I wouldn't mind spending the day cuddling with Dimaria

and joking around with God Serena

. My fav villians in FT right after Oracion Seis
Yup I always thought Dimaria is same age as Brandish (though my impression for her is same as Brandish. I thought she is an auntie lol). That's why they look so close to each other.
Jacob I think he is around 30-40 like Jura?
Now that you mention it, I am reminded of one of two unknown Spriggans. People said one of them is female. I personally don't think so. Coz usually girls always are so close to each other, gossipping, enjoying teatime together, having more screen than they are with boys/men (yea in our world it also applies lol). That's why Dimaria and Brandish had much screen time together. They even call each other with nickname. "Randy" and "Mary". But why they never mentioned this unknown Spriggan? This is why I think the unknown is not female. I don't even rely on that silhouette picture anymore.
Ultear and Meredy are close to each other. Same goes for Kamika and Cosmos, and Kyouka and Sayla...
But yea this depends on Mashima-sensei.