For my designs for the Weatherlight characters, I wanted to make sure that despite the powers some of them have, they remained balanced with other player characters, in case a player would want to integrate them into a party with other PCs. With Gerrard in particular, I reasoned that the high number of ability score increases that a Fighter can gain would be the best way to represent him being more powerful than the average human, while remaining balanced.
Further on this point, for Captain Sisay I designed a new type of variant human to keep her balanced despite her magic immunity, cutting down on the other benefits that humans gain to compensate for her main racial trait.
On a related note of general design for the Weatherlight party, I picked 10th-level for the Weatherlight characters as it still gives room to develop them in play, so things like gaining the further bonuses for Gerrard’s stats can come through playing the characters in a campaign, naturally building towards the higher power-level of some of these characters during the later stages of the Weatherlight Saga. For example, one could take the Magic Initiate feat for Orim, so that she could learn wizard or druid spells focused on water-manipulation, to represent the water magic she learned from the Cho-Arrim.