1) Stackability in PvP
Many Paragon skills have been nerfed because they stack so well with other Paragon players. Full teams of paragons would play untouchable, with no solid counters (or easily counterable counters) and it just wasn't fun for the other players. This means that ideally, skills should be effective and unique, but not significantly more effective with more copies. Some Echoes have already been fixed in PvP by limiting the number of triggers possible. This should allow the skills to be improved, but not in an exploitative way.
2) Damage and Utility in PvE
In PvE, AoE is king. The Paragon should be no exception to this. All other professions have some form of effective AoE. As for utility, improving the command line with a few very strong PvE-only skills would go a long way.
PvE-only changes: Anthem of Envy - (PvE Only) 6 adr, 1 cast Chant. "For 10 seconds, all allies in earshot do +5..20% more damage with spells and attacks to foes with more than 50% health." "Find Their Weakness!" - (PvE Only) 5 energy, 5 recharge Shout. "For 10..25 seconds, whenever target ally achieves a critical hit, that attack does +10..30 damage and inflicts a Deep Wound for 2..8 seconds." "Go for the Eyes!" - (PvE Only) 4 adr Shout. "For 10 seconds, the next 1..4 attacks for each ally within earshot has an additional 30...86...100% chance to critical." Slayer's Spear - (PvE Only) 5 energy, 2 recharge Spear Attack. "Deals +5..15 damage. Can hit up to 2 other foes near your target. Inflicts deep wound (5..20 seconds) on target if none of that target's allies are near it."
This relates to the stackability issue, because paragons aren't casters and their skills mostly benefit attacking classes. A great opportunity for command and leadership. If a paragon can help any class, then any class would like to have a paragon on board more often.
Hasty Refrain 10 energy, 1 cast, 10 recharge Echo. "For 8..16 seconds, target ally's spells recharge 10% faster for every chant or shout on that ally (maximum 5..30%). This Echo is reapplied every time a Chant or Shout ends on that ally" Song of Power 6 adr, 2 cast Chant. "For 10 seconds, all allies in earshot each gain +0..3 to their attributes for their next 1..3 spells. Ends on each ally if they cause damage with a spell."
When in a GvG split or an AB battle, paragons can get low on energy. Better options should be available. There is little ability for a paragon to maintain a shout on himself, and adrenline management is better on a Warrior.
"Make Your Time!" 10 energy, 20 recharge Shout. "You gain 1 strike of adrenaline for each party member within earshot (maximum 1...4...5 adrenaline). If there are less than 3..6 allies in earshot, you also gain 8..15 energy. For 15..30 seconds, your attack skills have +0..15% chance for a critical strike." "Lead the Way!" 10 enegy, 5 recharge Shout. "Target ally moves 25% faster and your paragon skills that target that ally cost 20..80% less energy for 1..6 seconds per ally in earshot (maximum 20 seconds). " Natural Temper - Increased duration to 5..20 seconds. Increased adrenaline gain to 50%.
Elite skills are meant to define a build or character, however the paragon has some of the least useful or interesting Elites in the game. To fix them is to fix them.
Cruel Spear 7 adr Elite Spear Attack. "Deals +1..31 damage. Inflicts Deep Wound condition for 5..20 seconds." Stunning Strike 8 adr, ½ cast Elite Spear Attack. "If target is not already Dazed, deals +15..40 damage and interrupts an action. Inflicts Dazed condition (4...9...10 seconds) if target has a condition." Crippling Anthem 6 adr, 1 cast Chant. "For 5 seconds, all allies in earshot move 15% faster and attack skills inflict Cripple for 5..10 seconds. Ends on each party member if they use a non-attack skill." Anthem of Guidance 6 adr, 1 cast Chant. "For 3..8 seconds, attacks made by party members in earshot that are blocked do 25..65 damage instead and give 0..2 adreniline to the attacking ally. Ends on each ally after 0..3 attacks." Cautery Signet 2 cast, 12 recharge Signet. "All allies in earshot lose all conditions. For each condition lost, you and foes in the area begin burning for one second."