Lumi is very useful as a healer with 45% of heal + heal over time for 2 turns, but in your case Wedge has already nice heal recovery so maybe consider farming Old Daka - good for DS and can revive allies or EE - for the same reasons, but light side.
And of course - farm Biggs. Read it out loud many times. Only combined with Biggs, Wedge can be great. Biggs triggers assists, where Wedge is involved too. Also Biggs got Wedge's unique. It would be very inbalanced to have good one folk and poor another in this duet.