pidhiyyare is cognate with the Sanskrit third person passive plural form pidhīyante (pidhīyate being singular) - from verb (a)pi-dhā (meaning ‘to shut’), where pi is an irregular contraction of for the preverb/upasarga ‘api’.
The -re at the end of the pali word (in my understanding) is actually a misreading of -te in the sanskrit original in the pre-pali manuscript (when the word is written in the Kharosthi script ‘te’ looks extremely similar to ‘re’) - from where Pali inherits this word (but it has evidently been thereafter regularized with the ‘re’ pl. ending in pali for most verbs).
te in kharoṣṭhī
re in kharoṣṭhī
The pali variant readings of this word (in the pārāyaṇavagga) are
- pithiyyare (sī. syā. pī.),
- pithīyare (sī. aṭṭha.),
- pidhīyare (?)
which indicates the word was sometimes written with a long medial ī (which was at other times converted into a iy) - but the reading of the final -re for the -te seems uniform.
The cūḷaniddesa gives a variant of the same word as explanation – kena sotā pidhiyyareti kena sotā pidhīyanti…
So does the atthakathā - kena sotā pidhiyyareti kena dhammena ete sotā pidhiyyanti
Yes. The final vārita in (sabbavārivārito) is a causative past passive participle form of the Skt. root vṛ – and means ‘has restrained’. The vāri (in sabbavāri) is, I think the Pāli-ization of the Sanskrit future passive participle form vārya (“has to be restrained”).
Hence the 4 bahuvrīhi compounds probably mean:
- sabba-vāri-vārito (sarva-vārya-vāritaḥ) = one who has restrained everything that had to be restrained.
- sabba-vāri-yutto (sarva-vārya-yuktaḥ) = one who adheres to all that’s supposed to be restrained – cf. Skt yukta
- sabba-vāri-dhuto (sarva-vārya-dhutaḥ) = one who has shaken-off (evil) by such a practice – cf. Skt dhuta
- sabba-vāri-phuṭo (sarva-vārya-sphuṭaḥ) = one who has manifested (in himself) all that’s to be restrained – cf. Skt sphuṭa