I think pilgrims shouldn't have shooting or edged weapons (only blunt)
Squires should be the shooting henchmen and maybe limit the number.
and 2-3 Men at Arms for Heroes give them not too bad starting stats as they are veteran warriors and possibly a long bow but no shooting skills save that for squires that become heroes.
Also a warband rule that if the Grail Knight Dies a Squire that is a hero Gains all the equipment of the dead knight and becomes leader but will no longer use any missile weapons.
I think a good idea for a hero would be a scribe or historian, with access to academics and speed but no spell casting and they could have skills just for the scribe rather than spells like
Tale o ye Vamprye: Any friendly warrior within 6" of this Hero is at +1 to wound a vampire, a roll of a one is always a failure.
Records of bravery: Choose a hero other than this warrior in the warband, Once per battle they may re-roll a failed leadership test. (this may be taken multiple times)
Tactics of thee savage: OrcsAny friendly warrior within 4" of this Hero is at +1 to hit in the first round of close combat when fighting Orcs.
Tactics of thee savage: BeastmenAny friendly warrior within 4" of this Hero is at +1 to hit in the first round of close combat when fighting Beastmen.
Almanac of antidotesDuring the shooting phase the scribe may restore one wound of an unengaged friendly warrior in base to base contact who lost a wound last turn with a poisoned weapon