What is 'The Vault' mentioned above?
I don't really know myself so here are my TWC house rules.
1.
Cost.
Simply add the cost of each weapon used in the combination.
Example: a fighter has a cost of 2/7 in 1-handed edged and 3/8 in 1-handed concussion. His cost to develop a broadsword/short sword TWC would be 4/14 while it'd be 5/15 for a broadsword/mace combo and 6/16 for a mace/warhammer combo.
Don't allow TWC for single cost weapons.
Example: another fighter has a cost of 2/7 in 1-handed edged and 9 in 1-handed concussion. He cannot develop any TWC based on a 1-handed concussion weapon.
Option: for single cost weapons, just add the first figure.
Example: the above fighter would be able to develop a broadsword/mace combo at a cost of 11, and a mace/warhammer combo at a cost of 18.
2.
Skill ranks:
One cannot develop more TWC skill ranks than the lowest of his skill ranks in the weapons involved in the TWC.
3.
Benefits:
* +5 to DB,
* Choice of the weapon table,
* Additional critical of the same severity of the type of the other weapon.
Example: a fighter has a broadsword/mace TWC and does a OB-DB of +133 against an AT17. It gives 12CS on the broadsword table and 16DK on the mace table. The fighter chooses to inflict 16DK and gains an additional DS critical.
Option: instead of allowing the character to "play" with two tables the whole time, make him choose one primary attack table and an additional critical type based on the other weapon involved in the TWC.
Example: a GM decides it to be too bothersome to "juggle" with two tables so he chooses this option. In the above case, the character decides to then always attack on the mace table, with an additional Slash critical of the same severity.
4.
Notice that only ONE attack roll is made, with the OB of the TWC skill.
5.
Additional benefits: as a fighter advances in his TWC, he gains additional benefits.
OB | # ranks | Benefits |
+120 | 15 | The DB bonus increases to +10 |
+140 | 20 | The fighter gains a +10 to his TWC OB |
+150 | 25 | The DB bonus increases to +15 |
+165 | 30 | The OB bonus increases to +20 |
Note: the OB column is the minimal "pure" OB, meaning the OB with the skill ranks, stat bonus and level bonus added only (i.e. without any bonus due to spells or items).
6.
Item bonus: if only one weapon has a bonus to hit, or each weapon has a different bonus, only the average bonus is added to the TWC skill.