Late reply, I know, but oh well.
IMO, both lines of weapon are amazing in their own right. The Eager Cleaver line has helped me hunt many a Tigrex / Kushala Daora / Daimyo Hermitaur / Anything weak to Thunder. The Wyvern Blade "Fall" line, likewise, has been instrumental in farming Rath- parts for their respective armour. Heck, the end-of-the-line weapon, Wyvern Blade "Camellia" was good enough for me to solo G-rank Ukanlos.
tl;dr: both weapons are good, just depends on what you hunt. IMO, you should get both.
...Wait, you hunted Rathalos/Rathian with the Wyyvern Blades? Which are Fire weapons? Uh...pretty sure they aren't weak to Fire. Last I checked, Dragon and Thunder were more effective. Also, I feel like compairing 2 weapons of different elements is like compairing apples and oranges, but I prefer the Wyvern Blades, since prefer Usurper's Boltslicers or pretty much any other non-awakening Thunder element blade (Aside from Thunder Clap) over the Eager Cleaver line. Though I might be underestimating the edge the 20% affinity gives.Â
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