• astrasya — of the weapon
  Genitive of astra. The kuśa-blade is named astra — once held by the Lord, the grass-tip is an astra. Its vīrya must not be retroactively undone; the killing must remain real.
• vīryasya — of valor / potency
  Vīrya = both heroism and potency. Balarāma's vīrya. The sages will not have the Lord humiliated by undoing His act. They ask for a solution that preserves His dignity along with the rite.
• mṛtyoḥ — of the death (Romaharṣaṇa's)
  Genitive of mṛtyu. They name even the death as something to preserve. Romaharṣaṇa's death must remain a fact — the sages will not pretend it didn't happen. Reality, not erasure, is the request.
• vacaḥ satyam — our word true
  Vacas (word) + satya (true). Their vow to Romaharṣaṇa must remain satya. Vedic culture treats kept-word as the substrate of cosmic order. The sages are asking the Lord to save their satyatā.
• vidhīyatām — let it be arranged
  Passive imperative of vi-√dhā. 'Let arrangement be made.' The sages turn the verb over to the Lord — He is the arranger of all forms, including this knot of four truths.

The sages compose a delicate request: preserve everything. Your weapon's power, Your own valor, our vow, and Romaharṣaṇa's death — all four must remain intact. They will not accept a solution that undoes any prior reality. The Lord is asked to keep every truth standing without contradiction. This is the form of the prayer.