Actually, the 5% lower defense growth makes almost no difference to Lucius. It doesn't have a significant impact on him... ever. It's not like he's ever going to not get 2HKOed.
The luck and stronger offensive stats are more useful. Overall, Lucius got a buff; which is misplaced since he's a pretty good unit.
Well, good point. I suppose Lucius' defense wouldn't really matter whether it was 10% or 5%, since it's pretty terrible anyway. But I still have to question that skill growth addition. Lucius' skill is good enough already and light magic is accurate. That +10% skill could go to defense, or luck, or somewhere else.