Your first statement is correct. However, what I feel needs to be checked out is your second statement. Wahl is not a mid-tier Spriggan...at all, he's low tier on the same level as Ajeel and Lessio...Dimaria is high mid tier, I'd honestly place her just below August, Eileen, Larcade and Invel (?)...she's stronger than everyone else in the Spriggan 12, and no, it isn't because of her Age Seal alone, she also has Chronos at her disposal, who's already stronger than Assault Wahl since Chronos's attacks could only be seen by a mage who had achieved their peak (Third Origin Sherria) and not by a fellow Time Mage (Ultear) , who mind you, earlier had cancelled out her Age Seal...
Chronos is probably faster than anyone else except the top 4 Spriggan 12 members...so Dimaria> Wahl
EDIT: I would also like to extend my congratulations to
@Axiomus for becoming a mod...you deserve it man