Difficulty / Strength problem

[Яowan]

I have two classes, one is a zombie class while the other a survivor class.

["vaegir_spearman_multiplayer","Tough Zombie","Tough Zombie",tf_guarantee_ranged|tf_guarantee_boots|tf_guarantee_armor|tf_guarantee_helmet|tf_guarantee_ranged|tf_guarantee_shield,0,0,fac_kingdom_2,
   [itm_zombie_gloves,itm_zombie_weapon,itm_zombie_head1,itm_zombie_armour1],
   def_attrib_multiplayer|str_14|level(45),wp_one_handed(80),knows_ironflesh_10|knows_power_strike_10,vaegir_face_young_1, vaegir_face_older_2],

As can been seen, the strength is '14'

Their weapon requires 20 str but they can equip it as they spawn with it (as intended) but for some reason, they can pick it back up when they drop it (Not much of a problem):

["zombie_weapon", "Basic Zombie Weapon", [("sickle",0)], itp_type_one_handed_wpn|itp_merchandise|itp_primary|itp_wooden_parry|itp_no_parry, itc_scimitar|itcf_carry_axe_left_hip, 
 180 , weight(0)|difficulty(20)|spd_rtng(105) | weapon_length(25)|swing_damage(40 , blunt) | thrust_damage(0 ,  pierce),imodbits_pick ],

Survivors class cannot pick up the zombie weapons, as intended:

["khergit_lancer_multiplayer","Infantry","Infantry",tf_mounted|tf_guarantee_all,0,0,fac_kingdom_3,
  [itm_hide_boots,itm_red_shirt],
  def_attrib_multiplayer|str_15|level(21),wp_crossbow(85)|wp_one_handed(120),knows_ironflesh_1|knows_shield_4|knows_power_strike_2|knows_athletics_1,khergit_face_middle_1, khergit_face_older_2],

And they can pick up their 15 str weapon:

["scottish_sword", "Scottish Sword", [("scottish_sword",0),("scottish_sword_scabbard", ixmesh_carry)], itp_type_one_handed_wpn|itp_merchandise|itp_primary, itc_longsword|itcf_carry_sword_left_hip|itcf_show_holster_when_drawn,
170 , weight(1.75)|difficulty(15)|spd_rtng(9 | weapon_length(81)|swing_damage(28 , cut) | thrust_damage(25 ,  pierce),imodbits_sword_high ],

And so can zombies, even though they have 14 str.

To sum up:
Zombies (14 str) can pick up 15 str weapons (Not intended).
Survivors, 15 str can pick up 15 str weapons as intended, and cannot pick up 20 str weapons, as intended.
I don't want zombies to be able to pick up the survivor weapons (They are all 15 str)

I'm a noob to all of this, and have tried to do what I know, but I can't manage to solve this. 
I'm sure it's something simple I've missed out on, but I can't get my head around it...

Could anyone please help me with this?
It becoming quite a problem with my mod, as zombies can pick up survivors' weapons, even though they do not have the strength requirement.

 

[Somebody]

Try playing around with the ti_on_item_picked_up trigger (although it doesn't seem to work in singleplayer) and agent_unequip_item.

 

[Яowan]

Try playing around with the ti_on_item_picked_up trigger (although it doesn't seem to work in singleplayer) and agent_unequip_item.

I'll try it, thanks.

I'll just make it so when a zombie swings one of the survivor weapons, they get removed, or I'll try making it so when they get picked up they get removed, whichever works.