Guild Wars 2

The reward for the achievement is a grand weapon chest, that states in it’s description “Contains your choice of a unique exotic weapon”

Precursors are an exotic weapon, so does this mean that we will be able to choose one as our reward?

your choice of a =/= your choice of any

nice try tho

You have a choice between one of the new named exotics.
No pres, no old named exotics.

The exotics are:

Truth
Anton’s Boot Blade
Knowledge is Power
Cobalt
Mecha Anchor
Impaler
Arc
Stardust
Shiverstone
Exterminator
Guild Defender
X6-31 Beta
Monsoon
Twin Talons
Occultist Flame
Rockweed Spire
Cutthroat Caller
Scepter of the Highborn
Phoenix Reborn
Beacon of Light
Komalie’s Sacrificial Blade
King’s Remembrance
Poyaqui’s Noggin
Crystal Guardian
Entropy
Genesis
Arthropoda
Levvi’s Detector
Combustion
Crustacea
Bonetti’s Rapier
Lord Taeres’s Shadow
Razah’s Nightmare
Song of the Temptress

You spent few hundreds on ascended, have a 50g exotic.