I wonder if that is 100 Arms masters as in the Mentalist Profession?
That would make a difference in a larger battle. Still, you attack with a manned force of 40k, with another 2k of horses and you will steamroll anyone with little effort. Especially 5100 trained soldiers and maybe another 10k militia.
But that begs the question. Do the Clans not fight as a unit? So you have 5000 standing soldiers that walk the highways and do watch tower duty, but in reality I think they have a very loose knit military structure. The Clans act as Standing Units but are not counted in the Military ladder.
You could go with a war like clan culture and you will have at least 40% of the entire population able to handle a weapon well and ride magnificently. 20k at any given time are able to pull their sword and throw spear and ride their horse to battle. Political games not with standing. You know like "You are so lucky we arrived in the nick of time!"
Of course there are the variables. Some clans are more war like then others, some are focused on creativity and others on the gift of horses. A few may even focus on herding, trade and what have you.
Just some thought from the peanut gallery.
E