Ah, might-finesse. My second most favourite build after pure magic. Glad that there are still people making videos about the game. It's criminaly overlooked. And to answer your question, I say mercantile with "c" having a "k" sound.
I love how you're digging so deep into some of the more oldschool RPGs! Would you ever consider covering the old Knights of the Old Republic games? Picked them up in the steam sale and have been having a blast of nostalgia and would love to see what you could come up with!