Based on Sri P.B. Annangaracharyar Swami's Commentary

Shloka 1:

	pAShaNDa dR^imaShaNDa dAvadahanashchArvAka shailAshani:
		bauddhadhvAnta nirAsa vAsarapatirjainebha kaNThIrava: |
	mAyAvAdi bhuja~Ngabha~NgagaruDastraividya chUDAmaNi:
		shrIra~Ngeshajayadhvajo vijayate rAmAnujoyam muni: ||

Meaning:

pAShaNDa dR^imaShaNDa dAva dahana: - Like a forest fire to the forest of Pashandas,
chArvAka shaila ashani:            - like thunder to Charvakas who are like mountains,
bauddhadhvAnta nirAsa vAsarapati:  - like the morning Sun to the darkness that is the 
                                     Bauddhas,
jaina ibha kaNThIrava:             - like a lion to Jainas who are like elephants,
mAyAvAdi bhuja~Nga bha~Nga garuDa  - like a Garuda to Mayavadis who are like snakes,
traividya chUDAmaNi:               - like an ornament worn on the crest to Vaidikas;
ayam                               - thus was present 
rAmAnuja: muni:                    - Ramanuja Muni,
shrIra~Ngesha vijayate jayadhvaja: - who placed the victory flag in Srirangam.

Commentary:
pAShaNDa dR^imaShaNDa dAva dahana::
Pashandas are nAstikas - those that do not accept that there is a Supreme and reject the Vedas as authoritative. They were spread everywhere like weeds. Ramanuja removed them completely - like a wild forest fire going through a forest. He was not like a small fire that needs dry twigs to burn; he was like a forest fire that burns even green trees. This comparison alsoe shows that he destroyed their philosophy very quickly.

This is what is shown in his vAzhi thirunAmam as "aRu samayach chedi adhanai adi aRuththAn vAzhiyE".

Thiruvarangaththamudhanar also states in his Ramanuja Nutrandhadhi "nAttiya nIsach samayangaL mANdana" and "thaRkach samaNarum sAkkiyap pEygaLum ... nIsarum mANdanar".

chArvAka shaila ashani::
Charvakas can be taken as an expansion of the word Pashandas; or it can be taken as Pashandas as well as Charvakas. Charvakas are those that believe that only those things that are visible to the eyes are true. Their philosophy is expressed as "pratyakshamekam chArvAka:". They stood rooted like mountains in this world and Ramanuja fell on them like thunder falls on mountains and broke them. This is similar to Indra using the Vajrayudha (the thunderbolt weapon) on the mountains.

bauddhadhvAnta nirAsa vAsarapati::
During Ramanuja's time, a darkness had surrounded the land due to the bauddha philosophy. As the sun known as Ramanuja rose (rAmAnuja divAkara:), this darkness was dispelled automatically - Thondaradippodi Azhvar's verse "kadhiravan guNa dhisai sigaram vandhaNaindhAn gana iruL aganRadhu" can be recalled here. This Sun did not have to reach its apex. Just as the darkness is dispelled at the advent of the early morning Sun, so too the bauddha philosophy was destroyed the moment Ramanuja was born.

jaina ibha kaNThIrava::
The Jainas were like elephants and Ramanuja became the lion that chased them away. In a forest where a lion rules, elephants would not exists and would get away - so to in the presence of Ramanuja, the Jainas had to retreat. Thiruvarangaththamudhanar calles Ramanuja as a strong lion that derived its strength from Thirumangai Azhvars verses "vali mikka sIyam irAmAnusan".

mAyAvAdi bhuja~Nga bha~Nga garuDa:
Mayavadis are those who state that everything is false or an illusion. If they are like serpents, then Ramanuja was like the Garuda whose very shadow was sufficient to destroy them.

traividya chUDAmaNi::
The Lord's panchAyudhas are weapons to those who oppose Him, but are ornaments to Him in the presence of His devotees. Similarly, while Ramanuja was as described above to those who rejected the Vedas and Sriman Naranaya, he too is an ornament to those who accept the Vedas. Thus he is like the ornament worn on top of the head, to Vaidikas.

shrIra~Ngesha vijayate jayadhvaja::
Ramanuja thus established the victory flag of Srivaishnava Sampradhayam in that most divine of places - Srirangam. Ramanuja is praised as "Srirangesha Jayadvaja". It is therefore that he is praised "thennarangar selvam muRRum thiruththi vaiththAn vAzhiyE", "manniya thennarangApuri mAmalai maRRum uvandhidu nAL" and Srivaishnavas echo his words everyday "srIman! srirangasriyam anupadravAm anudinam samvardhaya".