You can find new weapons and tank parts to equip your characters on the following Aces. I put it in the right order, episode-wise, so you don't miss anything while playing through.
To make it a bit easier, I will add pictures soon! (Inserting pics won't work the way I want it to as for some reason they don't load properly atm...)

Episode 2:
Enemy Ace: Segular The Wall
Item: ZM Kar 1 (Rifle)
Location: Northeast of The Edelweiß after it appears in turn 3. He is behind one of the trees between the houses.

Episode 3:
Enemy Ace: Ty The Immortal
Item: ZM MP 1 (Machine Gun)
Location: He is taking cover in the tall grass next to the ramp up at your offensive team's location.

Episode 5:
Enemy Ace: Lt. Nonnenkof
Item: ZM MP 2 (Machine Gun)
Location: In the southwest of the enemy base. If you're lucky (like I was), he will come running out of the base towards your road team so he is easy to finish off by tank. You have to kill him before the enemy retreats!

Episode 6:
Enemy Ace: Malya The Dust
Item: ZM SG 1 (Sniper Rifle)
Location: Northeastern part of the map behind an L-shaped wall.


Episode 7:
Enemy Ace: Kanazar The Lion
Item: ZM Kar 2 (Rifle)
Location: Arrives with Selvaria's group.

Episode 8, first half:
Enemy Ace: Ty The Immortal
Item: ZM MP 3 (Machine Gun)
Location: Northwestern part of the combat zone.

Episode 8, second half:
Enemy Ace: Zytreet The Lynx
Item: ZM SG 2 (Sniper Rifle)
Location: In the central area of the map.

Episode 10, first half:
Enemy Ace: Oswald The Iron
Item: ZM Kar 3 (Rifle)
Location: Can be found in the northwestern section of the map. Take the second trolley and shoot him with a sniper.

Episode 10, second half:
Enemy Ace: Tavyse The Beast
Item: ZM SG 3 (Sniper Rifle)
Location: Southeastern part of the map. Take the trolley.

Episode 11:
Enemy Ace: Capt. Nonnenkof
Item: VB FW 1
Location: Northwest of the imperial bas camp.

Episode 12:
Enemy Aces: Mash The Hunter & Yosnoa The Hound
Item: ZM SG 4 (Sniper Rifle) & Enhanced Block Pin (for the Edelweiß)
Location: Mash is the sniper in red, hiding behind sandbags. Yosnoa is the tank.

Episode 13:
Enemy Ace: Sima The Younger
Item: ZM Kar 4 (Rifle)
Location: In the western area of the combat zone behind the bunker.

Episode 14:
Enemy Ace: Sima The Elder
Item: ZM MP 4 (Machine Gun)
Location: He's the one who fires at a target right in the beginning of the mission.

Episode 15, first half:
Enemy Aces: Ozwald The Steel & Matz The Cleaner
Item: ZM Kar 5 (Rifle) & Firing Calculator (for the Edelweiß)
Location: He is taking cover in tall grass in the northeastern area of the map. Matz is a tank to the southwest of Ozwald's location.

Episode 16:
Enemy Ace: Shuntr The Mount
Item: ZM SG 5 (Sniper Rifle)
Location: He's a sniper at the end of the map.

Episode 17:
Enemy Ace: Ty The Immortal
Item: ZM MP 5 (Machine Gun)
Location: At the southwest regular enemy camp. He will go into an alley with sandbags - you can wait for him there if you want.

War Without Weapons:
Enemy Ace: Fujmolt the Edge
Item: VB FW 2
Location: In the second grass patch north of the tree. You have to kill him to win the mission, so don't have to search for him.

Flower Of The Battlefield:
Enemy Ace: Toiold The Bull
Item: Firing Calculator
Location: A big tank. You have to destroy it to win the battle, so don't have to search for him.