The tech is decided in the <Prereq> node, for example from CoreWeapons.xml:
<GameItemType InternalName="Mace">
<DisplayName>Mace</DisplayName>
<Description>Not designed for the subtle, the mace is deadly even in a peasant's hands.</Description>
<Type>Weapon</Type>
<WeaponType>Blunt</WeaponType>
<CanBeEquipped>1</CanBeEquipped>
<AdditionalTrainingTurns>16</AdditionalTrainingTurns>
<ShopValue>45</ShopValue>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_Attack_Blunt</StrVal>
<Value>15</Value>
</GameModifier>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_CombatSpeed</StrVal>
<Value>-3</Value>
</GameModifier>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_CurrentWeight</StrVal>
<Value>15</Value>
</GameModifier>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_BashChance</StrVal>
<Value>100</Value>
<Provides>Bash- Has a chance equal to the damage done of knocking the victim prone</Provides>
</GameModifier>
<IsAvailableForSovereignCustomization>0</IsAvailableForSovereignCustomization>
<Likelihood>200</Likelihood>
<RarityDisplay>Uncommon</RarityDisplay>
<Prereq>
<Type>Tech</Type>
<Attribute>Weaponsmithing</Attribute>
</Prereq>
<AIData AIPersonality="AI_General">
<AIPrefType>AIPrefType_BLUNT</AIPrefType>
<AIPriority>240</AIPriority>
</AIData>
<ArtDef>Mace_ArtDef</ArtDef>
<GameItemTypeArtDef InternalName="Mace_ArtDef">
<GameItemTypeModelPack InternalName="Mace_Default">
<IconFile>W_Mace_Icon_01.png</IconFile>
<TintR>0</TintR>
<TintG>0</TintG>
<TintB>0</TintB>
<AttackSFX>Hit_Hammer1</AttackSFX>
<AttackSFX>Hit_Hammer2</AttackSFX>
<AttackSFX>Hit_Hammer3</AttackSFX>
<EquipSFX>Equip_WoodenItem_01</EquipSFX>
<EquipSFX>Equip_WoodenItem_02</EquipSFX>
<EquipSFX>Equip_WoodenItem_03</EquipSFX>
<GameItemTypeModel>
<ModelFile>gfx/hkb/weapons/W_Mace_01.hkb</ModelFile>
<Texture_All>gfx/hkb/Weapons/FE_Weapons_01.png</Texture_All>
<Attachment>hand_right_Lcf</Attachment>
</GameItemTypeModel>
</GameItemTypeModelPack>
</GameItemTypeArtDef>
</GameItemType>
You can create a new sword to your fancy (remember to give it a unique internalname) or alter an existing one.
For example
<GameItemType InternalName="Shortsword_Practice_NEWWEAPON">
<Prereq>
<Type>Tech</Type>
<Attribute>Weaponsmithing</Attribute>
</Prereq>
<DisplayName>Practice Sword</DisplayName>
<Description>As slow and dull as those who use it - though over time at least the latter improves.</Description>
<Type>Weapon</Type>
<WeaponType>OneHanded</WeaponType>
<CanBeEquipped>1</CanBeEquipped>
<ShopValue>90</ShopValue>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_Attack_Cutting</StrVal>
<Value>9</Value>
</GameModifier>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_CurrentWeight</StrVal>
<Value>5</Value>
</GameModifier>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_MaxCounterAttack</StrVal>
<Value>1</Value>
<Provides>+1 Counterattack per round</Provides>
</GameModifier>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_ExpBonus</StrVal>
<Value>10</Value>
<Provides>+10% Experience</Provides>
</GameModifier>
<IsAvailableForSovereignCustomization>0</IsAvailableForSovereignCustomization>
<Likelihood>0</Likelihood>
<RarityDisplay>Common</RarityDisplay>
<HeroOnly>0</HeroOnly>
<IsAvailableForUnitDesign>1</IsAvailableForUnitDesign>
<AIData AIPersonality="AI_General">
<AIPrefType>AIPrefType_CUTTING</AIPrefType>
<AIPriority>260</AIPriority>
</AIData>
<ArtDef>Shortsword_Practice_ArtDef</ArtDef>
</GameItemType>
I also changed its liklihood so you don't start getting a lot of practice swords in random drops. Also changed <HeroOnly> to 0 and <IsAvailableForUnitDesign> to 1 so you can use it in unit designs.