The swords in question are the
Cutlaseer which is Lucia's starting weapon, the
Klyamoor which is found during
mission 3 and finally the
Zambak which is found in
Mission 10.
While they can be levelled past level 3 the trophy only requires you to reach level 3 and unlike the the Dante equivalent trophy
you only need to level up 1 sword.
To reach Level 3 with each sword you need to spend
15000 Red Orbs each,
5000 to reach level 2 and then
10000 to reach level 3.