It's actually my literal brother, and he's not someone who is feared. He's more of the type who would be admired and liked/love, than feared. Like yourself, he has a water moon that greatly influences his personality.
Where have you heard that having Mars in Sagittarius or Leo results in being feared?
That’s something I’ve observed based on how ppl I know with these placements are viewed mars in fire sign can make ppl wanna be around them, Mars is a masculine planet so when it’s in a masculine sign it makes the individual come across as tough. I’ve seen it everywhere online “don’t mess with a mars in aries” same can be said for any other fire mars sign