Rdm doesn't need stronger spells. Rdm is strong on its own. Its problem is that it can not bring anything to the table that can't be covered by another job that could do it better or at least similar. What Rdm really needs are unique spells that will give Rdm and certain direction that is different than the current setup.

Personally, I like the idea of Rdm as a functional front line mage. SE has been trying this for a long time and they failed at it. The frontline mage became either too weak in dealing damage or can not offer proper support. The only 'success' is Dancer but it's hard to argue Dancer being a 'mage'.

There are a few elements that can be unique to Rdm to allow Rdm to stay in the frontline, be effective as a DD but also good enough to be a support that people actually want.

New En-spell effect:
#1 Introduce enspell effect that reduce critical hit rate evasion (similar to Ninja's weapon Oirandori). Higher critical hit rate is a rare buff. This is an effect can allows the Rdm to stay in the front line and helps other DD to increase their damage. Similar to Dnc's Samba, this spell should not be resisted but it should have a short duration.
#2 Introduce an enspell effect that increases the target attack delay.

New Buff spell:
#1 Introduce a 'Rage' spell that will give a mild bonus to Attack while reduce Defense. Similar to Berserk but with a lower potency (roughly 12% to Atk and -12% to Def). This can be an "Aura" spell that can only be cast on the Rdm or a single target spell that can be used similar to Haste. I think having this spell with +50% in potency (roughly 20% increased in Atk) on the Rdm while under Composure effect would be necessary for Rdm to remain on the front line.
#2 Introduce a 'Fencer' spell that will increase evasion and accuracy but also increase critical damage taken. Also, allows an increased in potency when cast on the Rdm.
#3 Give Rdm and spell similar to earthen armor. This spell should be single target but persistence.
#4 Give Rdm the ability or spell to convert his MP into TP. 1MP for 1TP would be a little overpowered in some cases but 2 MP for 1 TP would be too weak to be useful.

Enhance current spells:
#1 Give equipments that increases Phalanx effect. Phalanx and Phalanx II were made with lv75 in mind. It would be ideal to have Rdm being able to increase the potency of Phalanx II to something more in line with lv119+