My group of friends and I have played Mordheim on and off for about 3 years now and over the last year or so we have made some house rules to balance things that didn't seem quite right to us.
It quickly became apparent that two hand weapons was easily the better option compared to one hand weapon and a buckler/shield. We also learned that while an axe was appropriately costed a club/mace/hammer was way too cheap for what it could do... I mean a dagger at 2gc was terrible compared to a club at 3gc (which would not only give concussion but will do it without giving a free armour save to the target). Other problems we had involved the long range penalty for pistols and throwing weapons which already had a maximum range that was small and seemed pointless to give it a long range penalty as most weapons have a longer short range.
To balance this we came up with the following house rules:
A model may be armed with two single handed weapons (one in their normal hand and one in the offhand), a model armed in this way will receive +1 attack in combat which must be made with the extra weapon held in the offhand. You will however receive a -1 to hit penalty with attacks made by a weapon in the offhand (decide which weapon is being used by the offhand before rolling to hit)
Defensive (Shields & Bucklers)
A warrior armed with a sword/axe/club (or any variants of these eg. Sigmarite Warhammer) and a shield or buckler will recieve a bonus +1 to their armour saves in combat (so where a model armed with a sword and a buckler would normally get no save in combat they will now get a 6+ instead or if armed with a sword and shield the normal 6+ would become a 5+. (This save can be combined with other armour as normal)
Close and Personal (Throwing Weapons and Pistols)
Thrown Weapons and Pistols do not suffer to hit penalties for shooting at long range.
Club/Mace/Hammer now costs 5gc for all warbands
Shields/Bucklers now cost 10gc for all warbands
We also thought of adding the "Ambidextrous" Skill to the combat skill list to allow a hero to ignore the -1 to hit penalty for using a weapon in the offhand.
Anyway these are our house rules, if you have any thoughts on these or maybe have a few house rules of your own I'd be interested to read them so feel free to post them.