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
to reach level 2 and then 10000
to reach level 3.