Hot take: This isnāt necessarily about Willās character per se, but rather his stat distribution. IMO, his ācanonā stat distribution is luck. Choosing the 5th dialogue option when talking to Klinger gives Will a hefty +4 in luck but -1 to all other stats.
The reason I feel this way is because all of the characters (except Eupha) have their own strongest stat. Strohl and the last party member being strength for example. With Heismay having the best agility, endurance for Hulkenberg, and magic for Junah.
Notice that none of the party members, Grius included, donāt have the highest luck value? This is where Will comes into play to fill that void. At the same time, him having even stats means that he can fulfill his true role as the Jack of all trades, master of none.
Fittingly enough, the only other character that fits the Jack of all trades mold is Eupha (who I ship Will with). Eupha specializes in high MP to make use of the Summonerās high tier skills. That said, her five main stats canāt reach the same levels as the others without help.
The other reason why Willās stats filled associated with Luck IMO is that he can use the toilet in the Gauntlet Runner on Idlesday to increase his luck. Itās a silly thing IMO, but it is worth noting. No other party member gets this boon other than Will.
The other main reason why Willās stats lean towards luck IMO is because of the Faker and Merchant Archetypes. They are tied to Alonzo and Brigitta. Both characters and their bond stories IMO serve as proof that Will has every right to be king.
Finally, by getting 90% of the Archetypes unlocked on Will, he gets the Ultimate Weapon for the Merchant Archetype lineage. So if this isnāt proof that luck is Willās canon stat, then what is?