IMHO, you bow to a noble to sacrifice pride. The most dangerous individuals in the past have been proud ones, typically with two names, instead of one. Water isn't as scarce as power in this world, not on a relative scale. If Tek has a power of 100, then your average commoner has .01. And giving that tiny little bit over to the noble or templar when you, reassures them you know better than to be proud, or think you have any power.
T'zai Byn chest-to-fist salute is an expression of ferocity and duty (merc's idea of duty), what started as pounding one's chest evolved into 'putting your weapon hand -before- your heart'. Don't think about what your doing, don't feel for the enemy, fuck, don't feel period. You show your superior what comes first, and that's your first, not your heart. You need your mind to fight, but if you've any 'heart' left over after the first year, you'd best hide it.
Just a thought, and something one of my PC's a long time ago believed about the two subjects after long periods of introspection.
And the spitting thing. Water witches are too well known in the Known World as existing, and if I were a noble, I wouldn't want the chance of those filthy, abominable beings casting their fluids at -ME-, Tek's mercy, no. I'd rather have them all lower themselves down before me, exposing their back (because my dagger's ready for it) than to waste what poor pitiful commoners think of as a rare resource.